Glen or Glenda: Empowering Users and Applications with Private Namespaces

Private name spaces were first introduced into Linux during the 2.5 kernel series. Their use has been limited due to name space manipulation being considered a privileged operation. Giving users and applications the ability to create private name spaces as well as the ability to mount and bind resources is the key to unlocking the full potential of this technology. There are serious performance, security and stability issues involved with user-controlled dynamic private name spaces in Linux. This paper proposes mechanisms and policies for maintaining system integrity while unlocking the power of dynamic name spaces for normal users. It discusses relevant potential applications of this technology including its use with FUSE (Filesystem in Userspace), V9FS (the Linux port of the Plan 9 resource sharing protocol) and Plan 9 from User Space (the Plan 9 application suite including user space synthetic file servers ported to UNIX variants).