| Namespaces compatibility list
|This document contains the information about the problems user
|may have when creating tasks living in different namespaces.
|Here's the summary. This matrix shows the known problems, that
|occur when tasks share some namespace (the columns) while living
|in different other namespaces (the rows):
| UTS IPC VFS PID User Net
|IPC X 1
|PID 1 1 X
|User 2 2 X
|1. Both the IPC and the PID namespaces provide IDs to address
| object inside the kernel. E.g. semaphore with IPCID or
| process group with pid.
| In both cases, tasks shouldn't try exposing this ID to some
| other task living in a different namespace via a shared filesystem
| or IPC shmem/message. The fact is that this ID is only valid
| within the namespace it was obtained in and may refer to some
| other object in another namespace.
|2. Intentionally, two equal user IDs in different user namespaces
| should not be equal from the VFS point of view. In other
| words, user 10 in one user namespace shouldn't have the same
| access permissions to files, belonging to user 10 in another
| The same is true for the IPC namespaces being shared - two users
| from different user namespaces should not access the same IPC objects
| even having equal UIDs.
| But currently this is not so.