Mount point removal and renaming

Posted Oct 17, 2013 12:56 UTC (Thu) by fishface60 (subscriber, #88700)
Parent article: Mount point removal and renaming

> But, if distributions are to ever enable user namespaces, these kinds
> of problems need to be found and fixed.

This is a problem independent of user namespaces.

linux-user-chroot[1] allows you to run commands in a separate mount
namespace, since it's a privileged suid helper.

I have a build tool that prevents builds from messing with my system,
by making most of my rootfs read-only.

Currently I hit this mount point removal problem if I try to build two
different things at once.

1: http://git.gnome.org/browse/linux-user-chroot/

Mount point removal and renaming

Posted Oct 17, 2013 18:44 UTC (Thu) by ebiederm (subscriber, #35028) [Link]

I do not know how you are hitting this problem but it sounds like even with my changes you will have a problem. Aka one build environment killing a file or directory the other build environment is using for a mount point.

That said I agree, that this can be a problem already.

One of the points of user namespaces is to take a bunch of kernel functionality we have been allowing non-root users to use for a long time and remove the need for the suid root helpers. Much like what happened with ptys with the introduction of /dev/ptmx.