zfs send -R (non-raw) of encrypted dataset does not work

[johnnyjacq16]

System information

Type	Version/Name
Distribution Name	CentOS & Arch
Distribution Version
Linux Kernel	4.18.0-193.6.3.el8_2.x86_64
Architecture	x86_64
ZFS Version	zstd-zfs
SPL Version	--

Problem 1

Describe the problem you're observing

zfs send -R SyS_Backup/ROOT/[email protected]_Harddrive-Backup | ssh 10.10.10.1 | zfs recv -v ztesting/Test 
&& echo 'done!'   
Pseudo-terminal will not be allocated because stdin is not a terminal.
cannot send SyS_Backup/ROOT/[email protected]_Harddrive-Backup: encrypted dataset SyS_Backup/ROOT/Arch_OS 
may not be sent with properties without the raw flag
[email protected]'s password:
cannot receive: failed to read from stream

Describe how to reproduce the problem

@ahrens I tied that but it did not work, I am using the zstd-zfs version of zfs, git clone from BrainSlayer git main or master branch (I taught on github the word master was to be changed to the word main but the main branch is still called master) , been using this version of zfs for the past 6 months having no issues from zstd perspective.

Show below is my setup:

[root@Cent_OS-box ~]# lsmod | grep zfs
zfs                  4530176  8
zunicode              335872  1 zfs
zzstd                 565248  1 zfs
zlua                  188416  1 zfs
zcommon                94208  1 zfs
znvpair                98304  2 zfs,zcommon
zavl                   16384  1 zfs
icp                   327680  1 zfs
spl                   118784  6 zfs,icp,zzstd,znvpair,zcommon,zavl

[root@Cent_OS-box ~]# zfs get compression,encryption,keyformat,keylocation SyS_Backup/ROOT/Arch_OS
NAME                     PROPERTY     VALUE           SOURCE
SyS_Backup/ROOT/Arch_OS  compression  zstd-19         inherited from SyS_Backup
SyS_Backup/ROOT/Arch_OS  encryption   aes-256-gcm     -
SyS_Backup/ROOT/Arch_OS  keyformat    passphrase      -
SyS_Backup/ROOT/Arch_OS  keylocation  prompt          local
[root@Cent_OS-box ~]# 

---

Problem 2

Describe the problem you're observing

pool cannot import

Describe how to reproduce the problem

Created a disk file use dd if=/dev/zero of= bs=4k Created two partition on the disk file using GTP partition table The first small partition contained vfat, and the second partition contained zfs I imported the pool successfully with the command zpool import -R <directory> -N <Original name> <New name> Removed some zfs dataset

Include any warning/errors/backtraces from the system logs

[ahrens]

The error message seems to be saying that what you're asking for is not implemented: encrypted dataset ... may not be sent with properties without the raw flag Note that -R means (among other things) "send with properties". Maybe @tcaputi can comment on why this restriction exists and what it might take to implement this. Presumably we would not want to send the encryption-related properties.

[tcaputi]

Yeah... So this was a bit complicated, but the gist of the reasoning goes something like this:

• Encryption is a property, but it is a setonce property. This allows us to enforce the fact that the encryption algorithm cant change over the life of the dataset (which is required for various reasons). setonce properties are not sent in a zfs send -p / -R stream.
• Encryption is also a property that "feels" like compression / checksum, which are not setonce properties. These properties ARE sent in a zfs send stream that includes properties. Users would reasonably expect that these properties would all "travel" together in a send stream.
• The only way to "send" the encryption property is to use raw streams.
• It would be bad if a user thinks that they were going to send data to an encrypted destination but that didn't happen. This could open up the end user to liability / security problems.
• In order to ensure the user gets reasonable results we force them to use zfs send -w when sending with properties.

If we can think of a better way to do this, I would be all for pursuing it. The key reasoning behind all this is that we really want to prevent the user from accidentally decrypting their data at all costs.

[bghira]

you would do that with an additional option, -X|--allow-decrypt

[clhedrick]

I see why this happens, but I think it might be useful to be able to do an unencypted backup. Our backup system is pretty secure. An extra option to zfs send that suppresses the encryption properties seems like the right approach. You can already omit pr override specitic properties.

in addition to allowing unencrypted backup, it lets you change your mind if you decide you don't want something encrypted.

[PhilZ-cwm6]

This also would make it possible to immediately apply a new encryption scheme/key on the receive side When we want a backup with a different encryption, currently:

• we need to create an encrypted pool on receive side, with its own encryption key
• send with -w
• we receive the migrated data with source encryption key, so different from the root receiving pool
• we cannot change the target encryption key, as it will be reset on next incremental replication tasks

Sadly, this is actually the only way to preserve dataset properties with encryption.

As said above, something like -R/-p --no-preserve-encryption would be useful and in that case, -w would be implicit with -p/-R so that things are not so confusing/unconventional for end users

[stewartadam]

+1 for a flag to send an unencrypted stream. I wanted to replicate existing datasets (including all properties and snapshots) from one pool to another with a new encrypted root (different algo + key) and as I understand it, I have to choose between two bad options:

1. send/recv all data with -R --raw which replicates everything but keeps the same key/algorithm on the new pool
2. send/recv all data without --raw which does re-encrypt the data under the new encryption root, but fails to replicate all previous snapshots or the dataset properties due to the inability to use -R

A --no-preserve-encryption flag to decrypt the encrypted dataset at the source (and therefore would permit -R to be used along side it) would permit for users to decrypt data at the source, permitting encrypted->unencrypted dataset replication or to re-encrypt datasets under new encryption roots.

[clhedrick]

I agree.

What I did was write a script that finds the oldest snapshot present on all file systems in the hierarchy. Then another script that sends that snapshot for each file system, individually. Once that has been done, incrementals can be done with -R. That’s going unencrypted to encrypted. I don’t know if it would work with an encrypted source.

We’re in the process of moving everything to encrypted, but I can’t do that on the source file systems until we move to a version where that doesn’t disable quotas.

There’s no question that a lot of work is needed on send receive involving encryption. I’d be willing to test, as long as the code would work on Ubuntu 20.04. We have a test server used just for staff files, and we could test on the backup server if there’s no danger of losing edistimg content.

On Nov 14, 2021, at 4:03 PM, Stewart Adam @.***> wrote:



+1 for a flag to send an unencrypted stream. I wanted to replicate existing datasets (including all properties and snapshots) from one pool to another with a new encrypted root (different algo + key) and as I understand it, I have to choose between two bad options:

1. send/recv all data with -R --raw which replicates everything but keeps the same key/algorithm on the new pool
2. send/recv all data without --raw which does re-encrypt the data under the new encryption root, but fails to replicate all previous snapshots or the dataset properties due to the inability to use -R

A --no-preserve-encryption flag to decrypt the encrypted dataset at the source (and therefore would permit -R to be used along side it) would permit for users to decrypt data from encrypted datasets, or to re-encrypt them under new roots.

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[DrGeek]

Hi ! Any news for this problem :( ?

[sotiris-bos]

I too need to replicate a system that has root on encrypted ZFS to a new system that will be unencrypted. Is there no way to do this other than rsync everything and manually set all the dataset properties?

~~This goes against the documentation for the -w flag: https://openzfs.github.io/openzfs-docs/man/8/zfs-send.8.html~~

[PhilZ-cwm6]

I too need to replicate a system that has root on encrypted ZFS to a new system that will be unencrypted. Is there no way to do this other than rsync everything and manually set all the dataset properties?

This goes against the documentation for the -w flag: https://openzfs.github.io/openzfs-docs/man/8/zfs-send.8.html

That's in fact another case where the --no-preserve-encryption would be helpful, sending data to an unencrypted dataset. Currently it is not possible to decrypt on target while using -R. So, in all cases, you loose all the dataset properties. It is like once you encrypt, you can never go back using zfs send. It is ok, but you have to be aware of the limitations, until a new option is added

[clhedrick]

You can send individual filesystems. It will send all snapshots.

• You need a script rather than a single command
• It doesn't preserve a few lesser-used features other than snapshots.

I agree that it would be good to be able to use -R while removing encryption. But for the moment, work on encryption should be centered on 11679. Nothing else should be done until that's fixed. It makes use of encryption at all dangerous.

---

From: PhilZ @.> Sent: Thursday, April 14, 2022 9:40 AM To: openzfs/zfs @.> Cc: Charles Hedrick @.>; Comment @.> Subject: Re: [openzfs/zfs] zfs send -R (non-raw) of encrypted dataset does not work (#10507)

I too need to replicate a system that has root on encrypted ZFS to a new system that will be unencrypted. Is there no way to do this other than rsync everything and manually set all the dataset properties?

This goes against the documentation for the -w flag: https://openzfs.github.io/openzfs-docs/man/8/zfs-send.8.html

That's in fact another case where the --no-preserve-encryption would be helpful, sending data to an unencrypted dataset. Currently it is not possible to decrypt on target while using -R. So, in all cases, you loose all the dataset properties. It is like once you encrypt, you can never go back using zfs send. It is ok, but you have to be aware of the limitations, until a new option is added

— Reply to this email directly, view it on GitHubhttps://github.com/openzfs/zfs/issues/10507#issuecomment-1099198517, or unsubscribehttps://github.com/notifications/unsubscribe-auth/AAORUCEGWKBPRWMJJDNPRJDVFAN4TANCNFSM4OKD55TA. You are receiving this because you commented.Message ID: @.***>

[PhilZ-cwm6]

You can send individual filesystems. It will send all snapshots. You need a script rather than a single command

No, you cannot send, as he asked, from encrypted, using -R or -p, without --raw So, for encrypted to decrypted operations, your only option is sending without preserving any property The alternative to preserve properties is the -R or -p WITH --raw, but you end up with an encrypted target having the same encryption as source

[sotiris-bos]

No, you cannot send, as he asked, from encrypted, using -R or -p, without --raw So, for encrypted to decrypted operations, your only option is sending without preserving any property The alternative to preserve properties is the -R or -p WITH --raw, but you end up with an encrypted target having the same encryption as source

This, the encryption is recursive, so if any of the above datasets are encrypted, then you cannot send the individual filesystems while retaining dataset properties.

I ended up sending without the -R flag and setting all the dataset properties manually.

[specious-logic]

I just ran into this as well. This is pretty bad for a number of the use cases other folks mentioned but also one I think is even worse.

The current operation forces you to accept either a) fragmented encryptionroot or b) you must always backup and restore the entire tree of datasets from encryptionroot down.

Imagine I have the following tree of datasets encrypt_root encrypt_root/parent1 encrypt_root/parent1/descendants ... encrypt_root/parent2 encrypt_root/parent2/descendants ...

I zfs raw send -Rw encrypt_root | zfs recv to another zpool. Maybe not desirable[1] but at least the structure of the tree is preserved.

Now for whatever reason I need to restore just encrypt_root/parent2 and its descendants. Given current operation encrypt_root/parent2 and its descendants will now have a variant encryptionroot that cannot be merged back to encrypt_root. And there is no way around this unless I write a script that grabs encrypt_root/parent2 and all its descendants one by one to restore.

Unless I have severely misunderstood something, this seems wrong.

[1] As other folks mentioned, it's entirely plausible I want the encryption harmonized to the zfs target not the source.

[PhilZ-cwm6]

I just ran into this as well. This is pretty bad for a number of the use cases other folks mentioned but also one I think is even worse.

The current operation forces you to accept either a) fragmented encryptionroot or b) you must always backup and restore the entire tree of datasets from encryptionroot down.

Imagine I have the following tree of datasets encrypt_root encrypt_root/parent1 encrypt_root/parent1/descendants ... encrypt_root/parent2 encrypt_root/parent2/descendants ...

I zfs raw send -Rw encrypt_root | zfs recv to another zpool. Maybe not desirable[1] but at least the structure of the tree is preserved.

Now for whatever reason I need to restore just encrypt_root/parent2 and its descendants. Given current operation encrypt_root/parent2 and its descendants will now have a variant encryptionroot that cannot be merged back to encrypt_root. And there is no way around this unless I write a script that grabs encrypt_root/parent2 and all its descendants one by one to restore.

Unless I have severely misunderstood something, this seems wrong.

[1] As other folks mentioned, it's entirely plausible I want the encryption harmonized to the zfs target not the source.

No, encryption is same on target, unless you modified it. So data in your case should be restored the same, that's what I found in all my tests if I remember well. The only issue is the inverse in fact, using different encryption on target while still preserving other properties of the dataset Currently, encryption is tied to all properties

[alexsmartens]

I'm trying to backup an encrypted zpool to an external drive and this doesn't to work because of the aforementioned issue. Any ides how to get around it in the meantime?

[alexsmartens]

seems like it would make sense to have a reference to a related problem on the other end of the pipe zfs receive -F

[wb14123]

I'm trying to migrate the encryption from ccm to gcm but this limitation prevent me from sending the dataset to another one with a different encryption algorithm.