Red Hat Summit9.16. Building automatically-enrollable VM images for cloud environments by using NBDE
Deploying automatically-enrollable encrypted images in a cloud environment can provide a unique set of challenges. As in other virtualization environments, you should reduce the number of instances started from a single image to avoid sharing the LUKS master key.
The best practice is to create customized images that are not shared in any public repository and that provide a base for the deployment of a limited amount of instances. The exact number of instances to create should be defined by deployment’s security policies and based on the risk tolerance associated with the LUKS master key attack vector.
To build LUKS-enabled automated deployments, systems such as Lorax or virt-install together with a Kickstart file should be used to ensure master key uniqueness during the image building process.
Cloud environments enable two Tang server deployment options:
- The Tang server can be deployed within the cloud environment itself. Deploying Tang natively in the cloud allows for easy deployment. However, given that it shares infrastructure with the data persistence layer of ciphertext of other systems, it might be possible for both the Tang server’s private key and the Clevis metadata to be stored on the same physical disk. Access to this physical disk permits a full compromise of the ciphertext data.
- The Tang server can be deployed outside of the cloud on independent infrastructure with a VPN link between the two infrastructures.
Always maintain a physical separation between the location where the data is stored and the system where Tang is running. This separation between the cloud and the Tang server ensures that the Tang server’s private key cannot be accidentally combined with the Clevis metadata. It also provides local control of the Tang server if the cloud infrastructure is at risk.
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