| 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): |
| 1. Both the IPC and the PID namespaces provide IDs to address |
| object inside the kernel. E.g. semaphore with IPCID or |
| 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 |
| But currently this is not so. |