Native Encryption for ZFS on Linux

This change incorporates three major pieces:

The first change is a keystore that manages wrapping
and encryption keys for encrypted datasets. These
commands mostly involve manipulating the new
DSL Crypto Key ZAP Objects that live in the MOS. Each
encrypted dataset has its own DSL Crypto Key that is
protected with a user's key. This level of indirection
allows users to change their keys without re-encrypting
their entire datasets. The change implements the new
subcommands "zfs load-key", "zfs unload-key" and
"zfs change-key" which allow the user to manage their
encryption keys and settings. In addition, several new
flags and properties have been added to allow dataset
creation and to make mounting and unmounting more
convenient.

The second piece of this patch provides the ability to
encrypt, decyrpt, and authenticate protected datasets.
Each object set maintains a Merkel tree of Message
Authentication Codes that protect the lower layers,
similarly to how checksums are maintained. This part
impacts the zio layer, which handles the actual
encryption and generation of MACs, as well as the ARC
and DMU, which need to be able to handle encrypted
buffers and protected data.

The last addition is the ability to do raw, encrypted
sends and receives. The idea here is to send raw
encrypted and compressed data and receive it exactly
as is on a backup system. This means that the dataset
on the receiving system is protected using the same
user key that is in use on the sending side. By doing
so, datasets can be efficiently backed up to an
untrusted system without fear of data being
compromised.

Reviewed by: Matthew Ahrens <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Jorgen Lundman <[email protected]>
Signed-off-by: Tom Caputi <[email protected]>
Closes #494 
Closes #5769 

1 files changed, 370 insertions, 5 deletions

diff --git a/man/man8/zfs.8 b/man/man8/zfs.8
index 44180d603..f344eb943 100644
--- a/man/man8/zfs.8
+++ b/man/man8/zfs.8
@@ -148,7 +148,7 @@
 .Cm mount
 .Nm
 .Cm mount
-.Op Fl Ov
+.Op Fl Olv
 .Op Fl o Ar options
 .Fl a | Ar filesystem
 .Nm
@@ -166,12 +166,12 @@
 .Ar snapshot bookmark
 .Nm
 .Cm send
-.Op Fl DLPRcenpv
+.Op Fl DLPRcenpvw
 .Op Oo Fl I Ns | Ns Fl i Oc Ar snapshot
 .Ar snapshot
 .Nm
 .Cm send
-.Op Fl Lce
+.Op Fl Lcew
 .Op Fl i Ar snapshot Ns | Ns Ar bookmark
 .Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot
 .Nm
@@ -270,6 +270,27 @@
 .Cm diff
 .Op Fl FHt
 .Ar snapshot Ar snapshot Ns | Ns Ar filesystem
+.Nm
+.Cm load-key
+.Op Fl nr
+.Op Fl L Ar keylocation
+.Fl a | Ar filesystem
+.Nm
+.Cm unload-key
+.Op Fl r
+.Fl a | Ar filesystem
+.Nm
+.Cm change-key
+.Op Fl l
+.Op Fl o Ar keylocation Ns = Ns Ar value
+.Op Fl o Ar keyformat Ns = Ns Ar value
+.Op Fl o Ar pbkdf2iters Ns = Ns Ar value
+.Ar filesystem
+.Nm
+.Cm change-key
+.Fl i
+.Op Fl l
+.Ar filesystem
 .Sh DESCRIPTION
 The
 .Nm
@@ -572,12 +593,36 @@ if the snapshot has been marked for deferred destroy by using the
 command.
 Otherwise, the property is
 .Sy off .
+.It Sy encryptionroot
+For encrypted datasets, indicates where the dataset is currently inheriting its
+encryption key from. Loading or unloading a key for the
+.Sy encryptionroot
+will implicitly load / unload the key for any inheriting datasets (see
+.Nm zfs Cm load-key
+and
+.Nm zfs Cm unload-key
+for details).
+Clones will always share an
+encryption key with their origin. See the
+.Sx Encryption
+section for details.
 .It Sy filesystem_count
 The total number of filesystems and volumes that exist under this location in
 the dataset tree.
 This value is only available when a
 .Sy filesystem_limit
 has been set somewhere in the tree under which the dataset resides.
+.It Sy keystatus
+Indicates if an encryption key is currently loaded into ZFS. The possible
+values are
+.Sy none ,
+.Sy available ,
+and
+.Sy unavailable .
+See
+.Nm zfs Cm load-key
+and
+.Nm zfs Cm unload-key .
 .It Sy guid
 The 64 bit GUID of this dataset or bookmark which does not change over its
 entire lifetime. When a snapshot is sent to another pool, the received
@@ -1218,6 +1263,93 @@ that doesn't support the large_dnode feature.
 .Pp
 This property can also be referred to by its shortened column name,
 .Sy dnsize .
+.It Xo
+.Sy encryption Ns = Ns Sy off Ns | Ns Sy on Ns | Ns Sy aes-128-ccm Ns | Ns
+.Sy aes-192-ccm Ns | Ns Sy aes-256-ccm Ns | Ns Sy aes-128-gcm Ns | Ns
+.Sy aes-192-gcm Ns | Ns Sy aes-256-gcm
+.Xc
+Controls the encryption cipher suite (block cipher, key length, and mode) used
+for this dataset. Requires the
+.Sy encryption
+feature to be enabled on the pool.
+Requires a
+.Sy keyformat
+to be set at dataset creation time.
+.Pp
+Selecting
+.Sy encryption Ns = Ns Sy on
+when creating a dataset indicates that the default encryption suite will be
+selected, which is currently
+.Sy aes-256-ccm .
+In order to provide consistent data protection, encryption must be specified at
+dataset creation time and it cannot be changed afterwards.
+.Pp
+For more details and caveats about encryption see the
+.Sy Encryption
+section.
+.It Sy keyformat Ns = Ns Sy raw Ns | Ns Sy hex Ns | Ns Sy passphrase
+Controls what format the user's encryption key will be provided as. This
+property is only set when the dataset is encrypted.
+.Pp
+Raw keys and hex keys must be 32 bytes long (regardless of the chosen
+encryption suite) and must be randomly generated. A raw key can be generated
+with the following command:
+.Bd -literal
+# dd if=/dev/urandom of=/path/to/output/key bs=32 count=1
+.Ed
+.Pp
+Passphrases must be between 8 and 512 bytes long and will be processed through
+PBKDF2 before being used (see the
+.Sy pbkdf2iters
+property). Even though the
+encryption suite cannot be changed after dataset creation, the keyformat can be
+with
+.Nm zfs Cm change-key .
+.It Xo
+.Sy keylocation Ns = Ns Sy prompt Ns | Ns Sy file:// Ns Em </absolute/file/path>
+.Xc
+Controls where the user's encryption key will be loaded from by default for
+commands such as
+.Nm zfs Cm load-key
+and
+.Nm zfs Cm mount Cm -l . This property is
+only set for encrypted datasets which are encryption roots. If unspecified, the
+default is
+.Sy prompt.
+.Pp
+Even though the encryption suite cannot be changed after dataset creation, the
+keylocation can be with either
+.Nm zfs Cm set
+or
+.Nm zfs Cm change-key .
+If
+.Sy prompt
+is selected ZFS will ask for the key at the command prompt when it is required
+to access the encrypted data (see
+.Nm zfs Cm load-key
+for details). This setting will also allow the key to be passed in via STDIN,
+but users should be careful not to place keys which should be kept secret on
+the command line. If a file URI is selected, the key will be loaded from the
+specified absolute file path.
+.It Sy pbkdf2iters Ns = Ns Ar iterations
+Controls the number of PBKDF2 iterations that a
+.Sy passphrase
+encryption key should be run through when processing it into an encryption key.
+This property is only defined when encryption is enabled and a keyformat of
+.Sy passphrase
+is selected. The goal of PBKDF2 is to significantly increase the
+computational difficulty needed to brute force a user's passphrase. This is
+accomplished by forcing the attacker to run each passphrase through a
+computationally expensive hashing function many times before they arrive at the
+resulting key. A user who actually knows the passphrase will only have to pay
+this cost once. As CPUs become better at processing, this number should be
+raised to ensure that a brute force attack is still not possible. The current
+default is
+.Sy 350000
+and the minimum is
+.Sy 100000 .
+This property may be changed with
+.Nm zfs Cm change-key .
 .It Sy exec Ns = Ns Sy on Ns | Ns Sy off
 Controls whether processes can be executed from within this file system.
 The default value is
@@ -2020,6 +2152,69 @@ and
 .Xr swapon 8
 commands. Do not swap to a file on a ZFS file system. A ZFS swap file
 configuration is not supported.
+.Ss Encryption
+Enabling the
+.Sy encryption
+feature allows for the creation of encrypted filesystems and volumes.
+.Nm
+will encrypt all user data including file and zvol data, file attributes,
+ACLs, permission bits, directory listings, FUID mappings, and userused /
+groupused data.
+.Nm
+will not encrypt metadata related to the pool structure, including dataset
+names, dataset hierarchy, file size, file holes, and dedup tables. Key rotation
+is managed internally by the  kernel module and changing the user's key does not
+require re-encrypting the entire dataset. Datasets can be scrubbed, resilvered,
+renamed, and deleted without the encryption keys being loaded (see the
+.Nm zfs Cm load-key
+subcommand for more info on key loading).
+.Pp
+Creating an encrypted dataset requires specifying the
+.Sy encryption
+and
+.Sy keyformat
+properties at creation time, along with an optional
+.Sy
+keylocation
+and
+.Sy pbkdf2iters .
+After entering an encryption key, the
+created dataset will become an encryption root. Any descendant datasets will
+inherit their encryption key from the encryption root, meaning that loading,
+unloading, or changing the key for the encryption root will implicitly do the
+same for all inheriting datasets. If this inheritence is not desired, simply
+supply a new
+.Sy encryption
+and
+.Sy keyformat
+when creating the child dataset or use
+.Nm zfs Cm change-key
+to break the relationship. The one exception is that clones will always use
+their origin's encryption key. Encryption root inheritence can be tracked via
+the read-only
+.Sy encryptionroot
+property.
+.Pp
+Encryption changes the behavior of a few
+.Nm
+operations. Encryption is applied after compression so compression ratios are
+preserved. Normally checksums in ZFS are 256 bits long, but for encrypted data
+the checksum is 128 bits of the user-chosen checksum and 128 bits of MAC from
+the encryption suite, which provides additional protection against maliciously
+altered data. Deduplication is still possible with encryption enabled but for
+security, datasets will only dedup against themselves, their snapshots, and
+their clones.
+.Pp
+There are a few limitations on encrypted datasets. Encrypted data cannot be
+embedded via the
+.Sy embedded_data
+feature. Encrypted datasets may not have
+.Sy copies Ns = Ns Em 3
+since the implementation stores some encryption metadata where the third copy
+would normally be. Since compression is applied before encryption datasets may
+be vulnerable to a CRIME-like attack if applications accessing the data allow
+for it. Deduplication with encryption will leak information about which blocks
+are equivalent in a dataset and will incur an extra CPU cost per block written.
 .Sh SUBCOMMANDS
 All subcommands that modify state are logged persistently to the pool in their
 original form.
@@ -2776,7 +2971,7 @@ Displays all ZFS file systems currently mounted.
 .It Xo
 .Nm
 .Cm mount
-.Op Fl Ov
+.Op Fl Olv
 .Op Fl o Ar options
 .Fl a | Ar filesystem
 .Xc
@@ -2798,6 +2993,15 @@ duration of the mount.
 See the
 .Sx Temporary Mount Point Properties
 section for details.
+.It Fl l
+Load keys for encrypted filesystems as they are being mounted. This is
+equivalent to executing
+.Nm zfs Cm load-key
+on each encryption root before mounting it. Note that if a filesystem has a
+.Sy keylocation
+of
+.Sy prompt
+this will cause the terminal to interactively block after asking for the key.
 .It Fl v
 Report mount progress.
 .El
@@ -2875,7 +3079,7 @@ feature.
 .It Xo
 .Nm
 .Cm send
-.Op Fl DLPRcenpv
+.Op Fl DLPRcenpvw
 .Op Oo Fl I Ns | Ns Fl i Oc Ar snapshot
 .Ar snapshot
 .Xc
@@ -2987,6 +3191,23 @@ option is not supplied in conjunction with
 .Fl c ,
 then the data will be decompressed before sending so it can be split into
 smaller block sizes.
+.It Fl w, -raw
+For encrypted datasets, send data exactly as it exists on disk. This allows
+backups to be taken even if encryption keys are not currently loaded. The
+backup may then be received on an untrusted machine since that machine will
+not have the encryption keys to read the protected data or alter it without
+being detected. Upon being received, the dataset will have the same encryption
+keys as it did on the send side, although the
+.Sy keylocation
+property will be defaulted to
+.Sy prompt
+if not otherwise provided. For unencrypted datasets, this flag will be
+equivalent to
+.Fl Lec .
+Note that if you do not use this flag for sending encrypted datasets, data will
+be sent unencrypted and may be re-encrypted with a different encryption key on
+the receiving system, which will disable the ability to do a raw send to that
+system for incrementals.
 .It Fl i Ar snapshot
 Generate an incremental stream from the first
 .Ar snapshot
@@ -3085,6 +3306,23 @@ option is not supplied in conjunction with
 .Fl c ,
 then the data will be decompressed before sending so it can be split into
 smaller block sizes.
+.It Fl w, -raw
+For encrypted datasets, send data exactly as it exists on disk. This allows
+backups to be taken even if encryption keys are not currently loaded. The
+backup may then be received on an untrusted machine since that machine will
+not have the encryption keys to read the protected data or alter it without
+being detected. Upon being received, the dataset will have the same encryption
+keys as it did on the send side, although the
+.Sy keylocation
+property will be defaulted to
+.Sy prompt
+if not otherwise provided. For unencrypted datasets, this flag will be
+equivalent to
+.Fl Lec .
+Note that if you do not use this flag for sending encrypted datasets, data will
+be sent unencrypted and may be re-encrypted with a different encryption key on
+the receiving system, which will disable the ability to do a raw send to that
+system for incrementals.
 .It Fl e, -embed
 Generate a more compact stream by using
 .Sy WRITE_EMBEDDED
@@ -3478,6 +3716,10 @@ diff             subcommand     Allows lookup of paths within a dataset
                                 given an object number, and the ability
                                 to create snapshots necessary to
                                 'zfs diff'.
+load-key         subcommand     Allows loading and unloading of encryption key
+                                (see 'zfs load-key' and 'zfs unload-key').
+change-key       subcommand     Allows changing an encryption key via
+                                'zfs change-key'.
 mount            subcommand     Allows mount/umount of ZFS datasets
 promote          subcommand     Must also have the 'mount' and 'promote'
                                 ability in the origin file system
@@ -3726,6 +3968,129 @@ arrows.
 .It Fl t
 Display the path's inode change time as the first column of output.
 .El
+.It Xo
+.Nm
+.Cm load-key
+.Op Fl nr
+.Op Fl L Ar keylocation
+.Fl a | Ar filesystem
+.Xc
+Load the key for
+.Ar filesystem ,
+allowing it and all children that inherit the
+.Sy keylocation
+property to be accessed. The key will be expected in the format specified by the
+.Sy keyformat
+and location specified by the
+.Sy keylocation
+property. Note that if the
+.Sy keylocation
+is set to
+.Sy prompt
+the terminal will interactively wait for the key to be entered. Loading a key
+will not automatically mount the dataset. If that functionality is desired,
+.Nm zfs Cm mount Sy -l
+will ask for the key and mount the dataset. Once the key is loaded the
+.Sy keystatus
+property will become
+.Sy available .
+.Bl -tag -width "-r"
+.It Fl r
+Recursively loads the keys for the specified filesystem and all descendent
+encryption roots.
+.It Fl a
+Loads the keys for all encryption roots in all imported pools.
+.It Fl n
+Do a dry-run
+.Pq Qq No-op
+load-key. This will cause zfs to simply check that the
+provided key is correct. This command may be run even if the key is already
+loaded.
+.It Fl L Ar keylocation
+Use
+.Ar keylocation
+instead of the
+.Sy keylocation
+property. This will not change the value of the property on the dataset. Note
+that if used with either
+.Fl r
+or
+.Fl a ,
+.Ar keylocation
+may only be given as
+.Sy prompt .
+.El
+.It Xo
+.Nm
+.Cm unload-key
+.Op Fl r
+.Fl a | Ar filesystem
+.Xc
+Unloads a key from ZFS, removing the ability to access the dataset and all of
+its children that inherit the
+.Sy keylocation
+property. This requires that the dataset is not currently open or mounted. Once
+the key is unloaded the
+.Sy keystatus
+property will become
+.Sy unavailable .
+.Bl -tag -width "-r"
+.It Fl r
+Recursively unloads the keys for the specified filesystem and all descendent
+encryption roots.
+.It Fl a
+Unloads the keys for all encryption roots in all imported pools.
+.El
+.It Xo
+.Nm
+.Cm change-key
+.Op Fl l
+.Op Fl o Ar keylocation Ns = Ns Ar value
+.Op Fl o Ar keyformat Ns = Ns Ar value
+.Op Fl o Ar pbkdf2iters Ns = Ns Ar value
+.Ar filesystem
+.Xc
+.It Xo
+.Nm
+.Cm change-key
+.Fl i
+.Op Fl l
+.Ar filesystem
+.Xc
+Allows a user to change the encryption key used to access a dataset. This
+command requires that the existing key for the dataset is already loaded into
+ZFS. This command may also be used to change the
+.Sy keylocation ,
+.Sy keyformat ,
+and
+.Sy pbkdf2iters
+properties as needed. If the dataset was not previously an encryption root it
+will become one. Alternatively, the
+.Fl i
+flag may be provided to cause an encryption root to inherit the parent's key
+instead.
+.Bl -tag -width "-r"
+.It Fl l
+Ensures the key is loaded before attempting to change the key. This is
+effectively equivalent to
+.Qq Nm zfs Cm load-key Ar filesystem ; Nm zfs Cm change-key Ar filesystem
+.It Fl o Ar property Ns = Ns Ar value
+Allows the user to set encryption key properties (
+.Sy keyformat ,
+.Sy keylocation ,
+and
+.Sy pbkdf2iters
+) while changing the key. This is the only way to alter
+.Sy keyformat
+and
+.Sy pbkdf2iters
+after the dataset has been created.
+.It Fl i
+Indicates that zfs should make
+.Ar filesystem
+inherit the key of its parent. Note that this command can only be run on an
+encryption root that has an encrypted parent.
+.El
 .El
 .Sh EXIT STATUS
 The