Volume Security

Harvester allows you to encrypt and decrypt virtual machine images. The encryption mechanism utilizes the Linux kernel module dm_crypt and the command-line utility cryptsetup.

Prerequisites

Prepare the following resources:

Secret: A Kubernetes secret is used as the passphrase of dm_crypt. You must specify the value of the CRYPTO_KEY_VALUE field. All other fields are fixed.

Example of a secret:

apiVersion: v1
kind: Secret
metadata:
  name: encryption
  namespace: default
data:
  CRYPTO_KEY_CIPHER: aes-xts-plain64
  CRYPTO_KEY_HASH: sha256
  CRYPTO_KEY_PROVIDER: secret
  CRYPTO_KEY_SIZE: 256
  CRYPTO_KEY_VALUE: "Your encryption passphrase"
  CRYPTO_PBKDF: argon2i

The example contains the default YAML code for Kubernetes secrets. Aside from this, you can use encryption options for LUKS mode, which is a cryptsetup operating mode. Harvester v1.4.1 and later versions support these options, but you must verify that these are supported by your nodes.

Option

Possible Values

CRYPTO_KEY_CIPHER

aes-xts-plain, aes-xts-plain64, aes-cbc-plain, aes-cbc-plain64, aes-cbc-essiv:sha256

CRYPTO_KEY_HASH

sha256, sha384, sha512

CRYPTO_KEY_SIZE

256, 384, 512

CRYPTO_PBKDF

argon2i, argon2id, pbkdf2

You can create a secret in the system namespace using kubectl or the Harvester UI (Edit as YAML feature). Resources in the system namespace are not displayed on the Harvester UI Secrets screen.

StorageClass: Images are encrypted using Longhorn, so required fields must be passed to the Longhorn CSI Driver. You can specify the encryption secret when creating a StorageClass. For more information, see Image StorageClass.

Example of a StorageClass:

allowVolumeExpansion: true
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: encryption
parameters:
  csi.storage.k8s.io/node-publish-secret-name: encryption
  csi.storage.k8s.io/node-publish-secret-namespace: default
  csi.storage.k8s.io/node-stage-secret-name: encryption
  csi.storage.k8s.io/node-stage-secret-namespace: default
  csi.storage.k8s.io/provisioner-secret-name: encryption
  csi.storage.k8s.io/provisioner-secret-namespace: default
  encrypted: "true"
  migratable: "true"
  numberOfReplicas: "3"
  staleReplicaTimeout: "2880"
provisioner: driver.longhorn.io
reclaimPolicy: Delete
volumeBindingMode: Immediate

You can create a secret in the system namespace using the Harvester UI (Edit as YAML feature) and kubectl. Resources in the system namespace are not displayed on the Harvester UI Secrets screen.

Encrypted Volumes

You can create an encrypted volume using an encrypted StorageClass on the following UI locations:

Volumes: Create screen
Volumes tab on the Virtual Machine: Create screen

Advanced Usage with Rancher Integration

The secret is an unencrypted Base64-encoded string. To keep the secret safe, you can use projects and namespaces to isolate permissions. For more information, see Multi-Tenancy.

Limitations

You cannot perform the following actions:

Export a new volume from an encrypted volume
Restore an encrypted volume to an unencrypted volume
Restore an unencrypted volume to an encrypted volume