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2 Namespaces compatibility list
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5 This document contains the information about the problems user
6 may have when creating tasks living in different namespaces.
8 Here's the summary. This matrix shows the known problems, that
9 occur when tasks share some namespace (the columns) while living
10 in different other namespaces (the rows):
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13 - UTS IPC VFS PID User Net
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23 1. 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.
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.
33 2. 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
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.
43 But currently this is not so.