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2User namespaces and resource control
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4
5The kernel contains many kinds of objects that either don't have
6individual limits or that have limits which are ineffective when
7a set of processes is allowed to switch their UID. On a system
8where the admins don't trust their users or their users' programs,
9user namespaces expose the system to potential misuse of resources.
10
11In order to mitigate this, we recommend that admins enable memory
12control groups on any system that enables user namespaces.
13Furthermore, we recommend that admins configure the memory control
14groups to limit the maximum memory usable by any untrusted user.
15
16Memory control groups can be configured by installing the libcgroup
17package present on most distros editing /etc/cgrules.conf,
18/etc/cgconfig.conf and setting up libpam-cgroup.
19