In the help text describing user namespaces recommend use of memory control groups. In many cases memory control groups are the only mechanism there is to limit how much memory a user who can create user namespaces can use. Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> --- Documentation/namespaces/resource-control.txt | 10 ++++++++++ init/Kconfig | 7 +++++++ 2 files changed, 17 insertions(+), 0 deletions(-) create mode 100644 Documentation/namespaces/resource-control.txt diff --git a/Documentation/namespaces/resource-control.txt b/Documentation/namespaces/resource-control.txt new file mode 100644 index 0000000..3d8178a --- /dev/null +++ b/Documentation/namespaces/resource-control.txt @@ -0,0 +1,10 @@ +There are a lot of kinds of objects in the kernel that don't have +individual limits or that have limits that are ineffective when a set +of processes is allowed to switch user ids. With user namespaces +enabled in a kernel for people who don't trust their users or their +users programs to play nice this problems becomes more acute. + +Therefore it is recommended that memory control groups be enabled in +kernels that enable user namespaces, and it is further recommended +that userspace configure memory control groups to limit how much +memory users they don't trust to play nice can use. diff --git a/init/Kconfig b/init/Kconfig index 7d30240..c8c58bd 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1035,6 +1035,13 @@ config USER_NS help This allows containers, i.e. vservers, to use user namespaces to provide different user info for different servers. + + When user namespaces are enabled in the kernel it is + recommended that the MEMCG and MEMCG_KMEM options also be + enabled and that user-space use the memory control groups to + limit the amount of memory a memory unprivileged users can + use. + If unsure, say N. config PID_NS -- 1.7.5.4 _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
