compatibility-list.rst (1494B)
1============================= 2Namespaces compatibility list 3============================= 4 5This document contains the information about the problems user 6may have when creating tasks living in different namespaces. 7 8Here's the summary. This matrix shows the known problems, that 9occur when tasks share some namespace (the columns) while living 10in different other namespaces (the rows): 11 12==== === === === === ==== === 13- UTS IPC VFS PID User Net 14==== === === === === ==== === 15UTS X 16IPC X 1 17VFS X 18PID 1 1 X 19User 2 2 X 20Net X 21==== === === === === ==== === 22 231. Both the IPC and the PID namespaces provide IDs to address 24 object inside the kernel. E.g. semaphore with IPCID or 25 process group with pid. 26 27 In both cases, tasks shouldn't try exposing this ID to some 28 other task living in a different namespace via a shared filesystem 29 or IPC shmem/message. The fact is that this ID is only valid 30 within the namespace it was obtained in and may refer to some 31 other object in another namespace. 32 332. Intentionally, two equal user IDs in different user namespaces 34 should not be equal from the VFS point of view. In other 35 words, user 10 in one user namespace shouldn't have the same 36 access permissions to files, belonging to user 10 in another 37 namespace. 38 39 The same is true for the IPC namespaces being shared - two users 40 from different user namespaces should not access the same IPC objects 41 even having equal UIDs. 42 43 But currently this is not so.