Re:Building untrusted container images safely at scale
by nyrikki on Monday June 30, 2025 @10:34AM
(#44423856)
Namespaces are not a security feature, they are... namespaces.
In k8s as an example, if you share your PID namespace in a pod, which is a simple config option, you can arbitrarily enter other pod member FS tree with /proc/PID/root, only protected by Unix permissions.
Without seacomp, capabilities, SELinux etc... anyone who can launch a docker container can use the --privlaged flag and change host firmware or view any filesystem including the hosts root.
Focusing on namespace breakout only misses most of the attack surface.
In k8s as an example, if you share your PID namespace in a pod, which is a simple config option, you can arbitrarily enter other pod member FS tree with /proc/PID/root, only protected by Unix permissions.
Without seacomp, capabilities, SELinux etc... anyone who can launch a docker container can use the --privlaged flag and change host firmware or view any filesystem including the hosts root.
Focusing on namespace breakout only misses most of the attack surface.