1=================================
2Documentation for /proc/sys/user/
3=================================
4
5kernel version 4.9.0
6
7Copyright (c) 2016		Eric Biederman <ebiederm@xmission.com>
8
9------------------------------------------------------------------------------
10
11This file contains the documentation for the sysctl files in
12/proc/sys/user.
13
14The files in this directory can be used to override the default
15limits on the number of namespaces and other objects that have
16per user per user namespace limits.
17
18The primary purpose of these limits is to stop programs that
19malfunction and attempt to create a ridiculous number of objects,
20before the malfunction becomes a system wide problem.  It is the
21intention that the defaults of these limits are set high enough that
22no program in normal operation should run into these limits.
23
24The creation of per user per user namespace objects are charged to
25the user in the user namespace who created the object and
26verified to be below the per user limit in that user namespace.
27
28The creation of objects is also charged to all of the users
29who created user namespaces the creation of the object happens
30in (user namespaces can be nested) and verified to be below the per user
31limits in the user namespaces of those users.
32
33This recursive counting of created objects ensures that creating a
34user namespace does not allow a user to escape their current limits.
35
36Currently, these files are in /proc/sys/user:
37
38max_cgroup_namespaces
39=====================
40
41  The maximum number of cgroup namespaces that any user in the current
42  user namespace may create.
43
44max_ipc_namespaces
45==================
46
47  The maximum number of ipc namespaces that any user in the current
48  user namespace may create.
49
50max_mnt_namespaces
51==================
52
53  The maximum number of mount namespaces that any user in the current
54  user namespace may create.
55
56max_net_namespaces
57==================
58
59  The maximum number of network namespaces that any user in the
60  current user namespace may create.
61
62max_pid_namespaces
63==================
64
65  The maximum number of pid namespaces that any user in the current
66  user namespace may create.
67
68max_time_namespaces
69===================
70
71  The maximum number of time namespaces that any user in the current
72  user namespace may create.
73
74max_user_namespaces
75===================
76
77  The maximum number of user namespaces that any user in the current
78  user namespace may create.
79
80max_uts_namespaces
81==================
82
83  The maximum number of user namespaces that any user in the current
84  user namespace may create.
85