Questions tagged [userns]

User namespaces or short `userns` is a facility that allows a sub-namespace to have its own set of UIDs and GIDs. This allows to use the least privilege principle for LXC containers, but it's not limited to that use case.

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Mounting Overlayfs in a user namespace

Is it possible to mount an Overlayfs filesystem as an unprivileged user in a user namespace in Linux kernels >4.3.3; it seems that the fix to this vulnerability has blocked this functionality entirely....
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I have trouble analysing the cause of this (firefox) segfault

When executed within a minimal (unprivileged) LXC container, firefox segfaults (other graphical applications work fine). I'am unable to find the exact cause of this segfault (which is most likely due ...
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276 views

How to map a UID to another UID (!= 0) inside a user namespace?

How can one map UID 1000 to another regular UID (not root/0) inside a user namespace? EDIT: For anyone interested, https://linuxcontainers.org/lxc/manpages/man5/lxc.container.conf.5.html lists an ...
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0answers
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Is it possible to register “virtual” user/group IDs in a Linux system?

Is there a standardized mechanism in Linux which can be used to tie usernames to user IDs without actually creating a system account that can log in? It would seem something like this is possible, ...
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0answers
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Why would creating a user namespace with size 1 work but size >1 fail

I am experimenting with unprivileged linux containers and I am writing a Go program that creates a minimalist container. The program forks itself and creates namespaces in the process. However for ...
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100 views

Is it allowed to assign one range of subordinate IDs to two different users?

Is it allowed to assign the same range of subordinate user and group IDs to different users on the system defining the subordinate IDs? Please provide sources for your answer. The idea here would be ...