44 lines
1.5 KiB
ReStructuredText
44 lines
1.5 KiB
ReStructuredText
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=============================
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Namespaces compatibility list
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=============================
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This document contains the information about the problems user
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may have when creating tasks living in different namespaces.
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Here's the summary. This matrix shows the known problems, that
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occur when tasks share some namespace (the columns) while living
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in different other namespaces (the rows):
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==== === === === === ==== ===
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- UTS IPC VFS PID User Net
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==== === === === === ==== ===
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UTS X
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IPC X 1
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VFS X
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PID 1 1 X
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User 2 2 X
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Net X
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==== === === === === ==== ===
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1. Both the IPC and the PID namespaces provide IDs to address
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object inside the kernel. E.g. semaphore with IPCID or
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process group with pid.
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In both cases, tasks shouldn't try exposing this ID to some
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other task living in a different namespace via a shared filesystem
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or IPC shmem/message. The fact is that this ID is only valid
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within the namespace it was obtained in and may refer to some
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other object in another namespace.
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2. Intentionally, two equal user IDs in different user namespaces
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should not be equal from the VFS point of view. In other
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words, user 10 in one user namespace shouldn't have the same
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access permissions to files, belonging to user 10 in another
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namespace.
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The same is true for the IPC namespaces being shared - two users
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from different user namespaces should not access the same IPC objects
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even having equal UIDs.
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But currently this is not so.
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