Gemini 1.5 Pro: This video is about user namespaces and how they are used in rootless containers. The speaker, Liz Rice from Aqua Security, starts by explaining what namespaces are and gives different examples of namespaces such as process id namespace and unix time-sharing system namespace. Then she dives into user namespaces. User namespaces map a user id from the host to a different id inside the container. This allows a non-privileged user to appear to be root inside the container. The speaker demonstrates this by running a shell as an unprivileged user and then unsharing the user namespace. She shows that inside the container, she appears to be running as nobody, but from the host perspective, she is still vagrant. One other interesting thing that can be done with user namespaces is to map the user id on the host to become root inside the container. The speaker demonstrates this as well. Even though she appears to be running as root inside the container, from the host perspective, she is still vagrant. This is because user namespaces provide a way to isolate the user id inside the container from the host. Another benefit of user namespaces is that they allow a non-privileged user to create other namespaces, such as a new uts namespace. The speaker demonstrates this by creating a new uts namespace and changing the hostname inside the container. However, from the host perspective, the hostname remains unchanged. In conclusion, user namespaces allow rootless containers to be created. Software inside those containers thinks it's running as root and has all the permissions it needs, but from the host perspective, it is not running as root. This is a major security improvement because it reduces the attack surface.
