9장. Creating SELinux policies for containers

To simplify creating new SELinux policies for custom containers, RHEL 10 provides the udica utility. You can use this tool to create a policy based on an inspection of the container JavaScript Object Notation (JSON) file, which contains Linux-capabilities, mount-points, and ports definitions. The tool consequently combines rules generated using the results of the inspection with rules inherited from a specified SELinux Common Intermediate Language (CIL) block.

The process of generating SELinux policy for a container using udica has three main parts:

During the parsing phase, udica looks for Linux capabilities, network ports, and mount points.

Based on the results, udica detects which Linux capabilities are required by the container and creates an SELinux rule allowing all these capabilities. If the container binds to a specific port, udica uses SELinux user-space libraries to get the correct SELinux label of a port that is used by the inspected container.

Afterward, udica detects which directories are mounted to the container file-system name space from the host.

The CIL’s block inheritance feature allows udica to create templates of SELinux allow rules focusing on a specific action, for example:

These templates are called blocks and the final SELinux policy is created by merging the blocks.