44 lines · plain
1=============================2Namespaces compatibility list3=============================4 5This document contains the information about the problems user6may have when creating tasks living in different namespaces.7 8Here's the summary. This matrix shows the known problems, that9occur when tasks share some namespace (the columns) while living10in different other namespaces (the rows):11 12==== === === === === ==== ===13- UTS IPC VFS PID User Net14==== === === === === ==== ===15UTS X16IPC X 117VFS X18PID 1 1 X19User 2 2 X20Net X21==== === === === === ==== ===22 231. Both the IPC and the PID namespaces provide IDs to address24 object inside the kernel. E.g. semaphore with IPCID or25 process group with pid.26 27 In both cases, tasks shouldn't try exposing this ID to some28 other task living in a different namespace via a shared filesystem29 or IPC shmem/message. The fact is that this ID is only valid30 within the namespace it was obtained in and may refer to some31 other object in another namespace.32 332. Intentionally, two equal user IDs in different user namespaces34 should not be equal from the VFS point of view. In other35 words, user 10 in one user namespace shouldn't have the same36 access permissions to files, belonging to user 10 in another37 namespace.38 39 The same is true for the IPC namespaces being shared - two users40 from different user namespaces should not access the same IPC objects41 even having equal UIDs.42 43 But currently this is not so.44