Confidential Containers

Introduction

The TEE OS supports containerized CAs and TAs. Figure 1 shows the overall architecture.

Figure 1 Architecture of confidential containers

• Docker engine: Core software used to run and manage containers. It is automatically installed when installing Docker.
• Container: An operating environment built based on user-defined images, including CAs and TAs.
• REE patch: A component in the REE, which is deployed on the host (libteec.so is deployed in the container to provide APIs) to enable the TrustZone environment. tlogcat is deployed on a host or in a container to view logs printed in the TEE.
• agentd: deployed in a container to dynamically load TAs in the container and support secure storage in the container.
• Hook: The hook mechanism supported by openEuler Docker in the REE enables resource allocation for confidential containers in the TEE.
• TEE cgroup: CPU and memory resources are allocated using control groups (cgroups) to confidential containers in the TEE.

For details about how to use this feature, see Confidential Containers.

Restrictions

• The TEE OS supports a maximum of 255 containers. However, considering the resource limitations in the TEE OS, the maximum number of containers that can run TAs concurrently is 63. If the maximum number is exceeded, TAs in new containers cannot be loaded.
• To use secure storage or HUK key derivation in a container, that container must be started using the hook mechanism.
• If a container is not started using the hook mechanism, the memory and CPU resources in the TEE are not restricted for that container.
• Use the Docker software package provided by openEuler because other Docker software packages may not support the hook mechanism.
• Currently no method is provided to observe the CPU usage in the TEE.
• By default only the root user can use cgroups in the TEE. You can add other authorized users to the trustlist.
• When a container is being used, modifying the Docker configuration in the REE may cause performance changes. For example, modifying data-root may deteriorate the secure storage performance in the container.