libpod: support for cgroup namespace

allow a container to run in a new cgroup namespace.

When running in a new cgroup namespace, the current cgroup appears to
be the root, so that there is no way for the container to access
cgroups outside of its own subtree.

By default it uses --cgroup=host to keep the previous behavior.

To create a new namespace, --cgroup=private must be provided.

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/pkg/spec/spec.go b/pkg/spec/spec.go
index 41054633f..a8ab4911a 100644
--- a/pkg/spec/spec.go
+++ b/pkg/spec/spec.go
@@ -325,6 +325,10 @@ func (config *CreateConfig) createConfigToOCISpec(runtime *libpod.Runtime, userM
 	if err := addIpcNS(config, &g); err != nil {
 		return nil, err
 	}
+
+	if err := addCgroupNS(config, &g); err != nil {
+		return nil, err
+	}
 	configSpec := g.Config
 
 	// HANDLE CAPABILITIES
@@ -622,6 +626,23 @@ func addIpcNS(config *CreateConfig, g *generate.Generator) error {
 	return nil
 }
 
+func addCgroupNS(config *CreateConfig, g *generate.Generator) error {
+	cgroupMode := config.CgroupMode
+	if cgroupMode.IsNS() {
+		return g.AddOrReplaceLinuxNamespace(string(spec.CgroupNamespace), NS(string(cgroupMode)))
+	}
+	if cgroupMode.IsHost() {
+		return g.RemoveLinuxNamespace(spec.CgroupNamespace)
+	}
+	if cgroupMode.IsPrivate() {
+		return g.AddOrReplaceLinuxNamespace(spec.CgroupNamespace, "")
+	}
+	if cgroupMode.IsContainer() {
+		logrus.Debug("Using container cgroup mode")
+	}
+	return nil
+}
+
 func addRlimits(config *CreateConfig, g *generate.Generator) error {
 	var (
 		kernelMax  uint64 = 1048576