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