Based on kernel version 4.15. Page generated on 2018-01-29 10:00 EST.
1 Namespaces compatibility list 2 3 This document contains the information about the problems user 4 may have when creating tasks living in different namespaces. 5 6 Here's the summary. This matrix shows the known problems, that 7 occur when tasks share some namespace (the columns) while living 8 in different other namespaces (the rows): 9 10 UTS IPC VFS PID User Net 11 UTS X 12 IPC X 1 13 VFS X 14 PID 1 1 X 15 User 2 2 X 16 Net X 17 18 1. Both the IPC and the PID namespaces provide IDs to address 19 object inside the kernel. E.g. semaphore with IPCID or 20 process group with pid. 21 22 In both cases, tasks shouldn't try exposing this ID to some 23 other task living in a different namespace via a shared filesystem 24 or IPC shmem/message. The fact is that this ID is only valid 25 within the namespace it was obtained in and may refer to some 26 other object in another namespace. 27 28 2. Intentionally, two equal user IDs in different user namespaces 29 should not be equal from the VFS point of view. In other 30 words, user 10 in one user namespace shouldn't have the same 31 access permissions to files, belonging to user 10 in another 32 namespace. 33 34 The same is true for the IPC namespaces being shared - two users 35 from different user namespaces should not access the same IPC objects 36 even having equal UIDs. 37 38 But currently this is not so.