295 lines
9.3 KiB
Groff
295 lines
9.3 KiB
Groff
.\"
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.\" CDDL HEADER START
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.\"
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.\" The contents of this file are subject to the terms of the
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.\" Common Development and Distribution License (the "License").
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.\" You may not use this file except in compliance with the License.
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.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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.\" or http://www.opensolaris.org/os/licensing.
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.\" See the License for the specific language governing permissions
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.\" and limitations under the License.
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.\" If applicable, add the following below this CDDL HEADER, with the
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.\" fields enclosed by brackets "[]" replaced with your own identifying
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.\" information: Portions Copyright [yyyy] [name of copyright owner]
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.\"
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.\" CDDL HEADER END
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.\"
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.\"
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.\" Copyright (c) 2009 Sun Microsystems, Inc. All Rights Reserved.
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.\" Copyright 2011 Joshua M. Clulow <josh@sysmgr.org>
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.\" Copyright (c) 2011, 2019 by Delphix. All rights reserved.
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.\" Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
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.\" Copyright (c) 2014, Joyent, Inc. All rights reserved.
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.\" Copyright (c) 2014 by Adam Stevko. All rights reserved.
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.\" Copyright (c) 2014 Integros [integros.com]
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.\" Copyright 2019 Richard Laager. All rights reserved.
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.\" Copyright 2018 Nexenta Systems, Inc.
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.\" Copyright 2019 Joyent, Inc.
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.\"
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.Dd January 13, 2020
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.Dt ZFS-LOAD-KEY 8
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.Os
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.Sh NAME
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.Nm zfs-load-key
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.Nd Load, unload, or change the encryption key used to access a dataset.
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.Sh SYNOPSIS
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.Nm zfs
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.Cm load-key
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.Op Fl nr
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.Op Fl L Ar keylocation
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.Fl a | Ar filesystem
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.Nm zfs
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.Cm unload-key
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.Op Fl r
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.Fl a | Ar filesystem
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.Nm zfs
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.Cm change-key
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.Op Fl l
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.Op Fl o Ar keylocation Ns = Ns Ar value
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.Op Fl o Ar keyformat Ns = Ns Ar value
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.Op Fl o Ar pbkdf2iters Ns = Ns Ar value
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.Ar filesystem
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.Nm zfs
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.Cm change-key
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.Fl i
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.Op Fl l
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.Ar filesystem
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.Sh DESCRIPTION
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.Bl -tag -width ""
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.It Xo
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.Nm zfs
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.Cm load-key
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.Op Fl nr
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.Op Fl L Ar keylocation
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.Fl a | Ar filesystem
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.Xc
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Load the key for
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.Ar filesystem ,
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allowing it and all children that inherit the
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.Sy keylocation
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property to be accessed. The key will be expected in the format specified by the
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.Sy keyformat
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and location specified by the
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.Sy keylocation
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property. Note that if the
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.Sy keylocation
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is set to
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.Sy prompt
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the terminal will interactively wait for the key to be entered. Loading a key
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will not automatically mount the dataset. If that functionality is desired,
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.Nm zfs Cm mount Sy -l
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will ask for the key and mount the dataset
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.Po
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see
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.Xr zfs-mount 8
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.Pc .
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Once the key is loaded the
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.Sy keystatus
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property will become
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.Sy available .
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.Bl -tag -width "-r"
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.It Fl r
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Recursively loads the keys for the specified filesystem and all descendent
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encryption roots.
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.It Fl a
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Loads the keys for all encryption roots in all imported pools.
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.It Fl n
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Do a dry-run
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.Pq Qq No-op
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load-key. This will cause zfs to simply check that the
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provided key is correct. This command may be run even if the key is already
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loaded.
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.It Fl L Ar keylocation
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Use
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.Ar keylocation
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instead of the
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.Sy keylocation
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property. This will not change the value of the property on the dataset. Note
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that if used with either
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.Fl r
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or
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.Fl a ,
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.Ar keylocation
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may only be given as
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.Sy prompt .
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.El
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.It Xo
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.Nm zfs
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.Cm unload-key
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.Op Fl r
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.Fl a | Ar filesystem
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.Xc
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Unloads a key from ZFS, removing the ability to access the dataset and all of
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its children that inherit the
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.Sy keylocation
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property. This requires that the dataset is not currently open or mounted. Once
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the key is unloaded the
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.Sy keystatus
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property will become
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.Sy unavailable .
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.Bl -tag -width "-r"
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.It Fl r
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Recursively unloads the keys for the specified filesystem and all descendent
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encryption roots.
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.It Fl a
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Unloads the keys for all encryption roots in all imported pools.
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.El
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.It Xo
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.Nm zfs
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.Cm change-key
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.Op Fl l
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.Op Fl o Ar keylocation Ns = Ns Ar value
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.Op Fl o Ar keyformat Ns = Ns Ar value
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.Op Fl o Ar pbkdf2iters Ns = Ns Ar value
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.Ar filesystem
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.Xc
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.It Xo
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.Nm zfs
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.Cm change-key
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.Fl i
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.Op Fl l
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.Ar filesystem
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.Xc
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Changes the user's key (e.g. a passphrase) used to access a dataset. This
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command requires that the existing key for the dataset is already loaded into
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ZFS. This command may also be used to change the
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.Sy keylocation ,
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.Sy keyformat ,
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and
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.Sy pbkdf2iters
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properties as needed. If the dataset was not previously an encryption root it
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will become one. Alternatively, the
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.Fl i
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flag may be provided to cause an encryption root to inherit the parent's key
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instead.
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.Pp
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If the user's key is compromised,
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.Nm zfs Cm change-key
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does not necessarily protect existing or newly-written data from attack.
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Newly-written data will continue to be encrypted with the same master key as
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the existing data. The master key is compromised if an attacker obtains a
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user key and the corresponding wrapped master key. Currently,
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.Nm zfs Cm change-key
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does not overwrite the previous wrapped master key on disk, so it is
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accessible via forensic analysis for an indeterminate length of time.
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.Pp
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In the event of a master key compromise, ideally the drives should be securely
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erased to remove all the old data (which is readable using the compromised
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master key), a new pool created, and the data copied back. This can be
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approximated in place by creating new datasets, copying the data
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(e.g. using
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.Nm zfs Cm send
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.Nm zfs Cm recv Ns
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), and then clearing the free space with
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.Nm zpool Cm trim --secure
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if supported by your hardware, otherwise
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.Nm zpool Cm initialize Ns .
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.Bl -tag -width "-r"
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.It Fl l
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Ensures the key is loaded before attempting to change the key. This is
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effectively equivalent to
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.Qq Nm zfs Cm load-key Ar filesystem ; Nm zfs Cm change-key Ar filesystem
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.It Fl o Ar property Ns = Ns Ar value
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Allows the user to set encryption key properties (
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.Sy keyformat ,
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.Sy keylocation ,
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and
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.Sy pbkdf2iters
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) while changing the key. This is the only way to alter
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.Sy keyformat
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and
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.Sy pbkdf2iters
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after the dataset has been created.
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.It Fl i
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Indicates that zfs should make
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.Ar filesystem
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inherit the key of its parent. Note that this command can only be run on an
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encryption root that has an encrypted parent.
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.El
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.El
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.Ss Encryption
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Enabling the
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.Sy encryption
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feature allows for the creation of encrypted filesystems and volumes. ZFS
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will encrypt file and zvol data, file attributes, ACLs, permission bits,
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directory listings, FUID mappings, and
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.Sy userused
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/
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.Sy groupused
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data. ZFS will not encrypt metadata related to the pool structure, including
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dataset and snapshot names, dataset hierarchy, properties, file size, file
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holes, and deduplication tables (though the deduplicated data itself is
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encrypted).
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.Pp
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Key rotation is managed by ZFS. Changing the user's key (e.g. a passphrase)
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does not require re-encrypting the entire dataset. Datasets can be scrubbed,
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resilvered, renamed, and deleted without the encryption keys being loaded (see the
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.Nm zfs Cm load-key
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subcommand for more info on key loading).
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.Pp
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Creating an encrypted dataset requires specifying the
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.Sy encryption
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and
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.Sy keyformat
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properties at creation time, along with an optional
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.Sy keylocation
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and
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.Sy pbkdf2iters .
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After entering an encryption key, the
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created dataset will become an encryption root. Any descendant datasets will
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inherit their encryption key from the encryption root by default, meaning that
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loading, unloading, or changing the key for the encryption root will implicitly
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do the same for all inheriting datasets. If this inheritance is not desired,
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simply supply a
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.Sy keyformat
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when creating the child dataset or use
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.Nm zfs Cm change-key
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to break an existing relationship, creating a new encryption root on the child.
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Note that the child's
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.Sy keyformat
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may match that of the parent while still creating a new encryption root, and
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that changing the
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.Sy encryption
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property alone does not create a new encryption root; this would simply use a
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different cipher suite with the same key as its encryption root. The one
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exception is that clones will always use their origin's encryption key.
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As a result of this exception, some encryption-related properties (namely
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.Sy keystatus ,
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.Sy keyformat ,
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.Sy keylocation ,
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and
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.Sy pbkdf2iters )
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do not inherit like other ZFS properties and instead use the value determined
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by their encryption root. Encryption root inheritance can be tracked via the
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read-only
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.Sy encryptionroot
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property.
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.Pp
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Encryption changes the behavior of a few ZFS
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operations. Encryption is applied after compression so compression ratios are
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preserved. Normally checksums in ZFS are 256 bits long, but for encrypted data
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the checksum is 128 bits of the user-chosen checksum and 128 bits of MAC from
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the encryption suite, which provides additional protection against maliciously
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altered data. Deduplication is still possible with encryption enabled but for
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security, datasets will only dedup against themselves, their snapshots, and
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their clones.
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.Pp
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There are a few limitations on encrypted datasets. Encrypted data cannot be
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embedded via the
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.Sy embedded_data
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feature. Encrypted datasets may not have
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.Sy copies Ns = Ns Em 3
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since the implementation stores some encryption metadata where the third copy
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would normally be. Since compression is applied before encryption datasets may
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be vulnerable to a CRIME-like attack if applications accessing the data allow
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for it. Deduplication with encryption will leak information about which blocks
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are equivalent in a dataset and will incur an extra CPU cost per block written.
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.Sh SEE ALSO
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.Xr zfs-create 8 ,
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.Xr zfs-set 8 ,
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.Xr zfsprops 8
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