Allow to adjust LinuxNamespaces

README.md

@@ -254,6 +254,7 @@ container parameters:
       - Block I/O class
       - RDT class
       - Linux seccomp policy
+    - Linux namespaces
 
 ### Container Updates
 
@@ -349,11 +350,14 @@ for rejecting adjustment of the seccomp policy profile based on the type of poli
 profile set for the container. These types include the runtime default seccomp
 policy profile, a custom policy profile, and unconfined security profiles.
 
-3. Verify global mandatory plugins: Verify that all configured mandatory
+3. Reject Linux Namespace adjustment: Reject any adjustment which tries to
+alter Linux namespaces of a container.
+
+4. Verify global mandatory plugins: Verify that all configured mandatory
 plugins are present and have processed a container. Otherwise reject the
 creation of the container.
 
-4. Verify annotated mandatory plugins: Verify that an annotated set of
+5. Verify annotated mandatory plugins: Verify that an annotated set of
 container-specific mandatory plugins are present and have processed a
 container. Otherwise reject the creation of the container.
 
@@ -362,11 +366,11 @@ allows one to deploy mandatory plugins as containers themselves.
 
 #### Default Validation Scope
 
-Currently only OCI hook injection and Linux seccomp policy can be restricted
-using the default validator. However, this probably will change in the future.
-Especially when NRI is extended with control over more container parameters.
-If newly added controls will have security implications, expect corresponding
-configurable restrictions in the default validator.
+Currently only OCI hook injection, Linux seccomp policy and Linux namespace
+adjustment can be restricted using the default validator. However, this probably
+will change in the future. Especially when NRI is extended with control over more
+container parameters. If newly added controls will have security implications,
+expect corresponding configurable restrictions in the default validator.
 
 ## Runtime Adaptation
 

pkg/adaptation/adaptation_suite_test.go

@@ -505,6 +505,12 @@ var _ = Describe("Plugin container creation adjustments", func() {
 			}
 			a.AddDevice(dev)
 
+		case "namespace":
+			ns := &api.LinuxNamespace{
+				Type: "cgroup",
+			}
+			a.AddOrReplaceNamespace(ns)
+
 		case "rlimit":
 			a.AddRlimit("nofile", 456, 123)
 
@@ -716,6 +722,17 @@ var _ = Describe("Plugin container creation adjustments", func() {
 					},
 				},
 			),
+			Entry("adjust namespace", "namespace",
+				&api.ContainerAdjustment{
+					Linux: &api.LinuxContainerAdjustment{
+						Namespaces: []*api.LinuxNamespace{
+							{
+								Type: "cgroup",
+							},
+						},
+					},
+				},
+			),
 			Entry("adjust rlimits", "rlimit",
 				&api.ContainerAdjustment{
 					Rlimits: []*api.POSIXRlimit{{Type: "nofile", Soft: 123, Hard: 456}},
@@ -1800,6 +1817,94 @@ var _ = Describe("Plugin container creation adjustments", func() {
 		})
 	})
 
+	When("the default validator is enabled and namespace adjustment is disabled", func() {
+		BeforeEach(func() {
+			s.Prepare(
+				&mockRuntime{
+					options: []nri.Option{
+						nri.WithDefaultValidator(
+							&validator.DefaultValidatorConfig{
+								Enable:                    true,
+								RejectNamespaceAdjustment: true,
+							},
+						),
+					},
+				},
+				&mockPlugin{idx: "00", name: "foo"},
+				&mockPlugin{idx: "10", name: "validator1"},
+				&mockPlugin{idx: "20", name: "validator2"},
+			)
+		})
+
+		It("should reject namespace adjustment", func() {
+			var (
+				create = func(_ *mockPlugin, _ *api.PodSandbox, ctr *api.Container) (*api.ContainerAdjustment, []*api.ContainerUpdate, error) {
+					a := &api.ContainerAdjustment{}
+					if ctr.GetName() == "ctr1" {
+						a.AddOrReplaceNamespace(
+							&api.LinuxNamespace{
+								Type: "cgroup",
+								Path: "/",
+							},
+						)
+					}
+					return a, nil, nil
+				}
+
+				validate = func(_ *mockPlugin, _ *api.ValidateContainerAdjustmentRequest) error {
+					return nil
+				}
+
+				runtime = s.runtime
+				plugins = s.plugins
+				ctx     = context.Background()
+
+				pod = &api.PodSandbox{
+					Id:        "pod0",
+					Name:      "pod0",
+					Uid:       "uid0",
+					Namespace: "default",
+				}
+				ctr0 = &api.Container{
+					Id:           "ctr0",
+					PodSandboxId: "pod0",
+					Name:         "ctr0",
+					State:        api.ContainerState_CONTAINER_CREATED,
+				}
+				ctr1 = &api.Container{
+					Id:           "ctr1",
+					PodSandboxId: "pod0",
+					Name:         "ctr1",
+					State:        api.ContainerState_CONTAINER_CREATED,
+				}
+			)
+
+			plugins[0].createContainer = create
+			plugins[1].validateAdjustment = validate
+			plugins[2].validateAdjustment = validate
+
+			s.Startup()
+			podReq := &api.RunPodSandboxRequest{Pod: pod}
+			Expect(runtime.RunPodSandbox(ctx, podReq)).To(Succeed())
+
+			ctrReq := &api.CreateContainerRequest{
+				Pod:       pod,
+				Container: ctr0,
+			}
+			reply, err := runtime.CreateContainer(ctx, ctrReq)
+			Expect(reply).ToNot(BeNil())
+			Expect(err).To(BeNil())
+
+			ctrReq = &api.CreateContainerRequest{
+				Pod:       pod,
+				Container: ctr1,
+			}
+			reply, err = runtime.CreateContainer(ctx, ctrReq)
+			Expect(err).ToNot(BeNil())
+			Expect(reply).To(BeNil())
+		})
+	})
+
 	When("the default validator is enabled with some required plugins", func() {
 		const AnnotationDomain = plugin.AnnotationDomain
 		BeforeEach(func() {

pkg/adaptation/result.go

@@ -18,6 +18,7 @@ package adaptation
 
 import (
 	"fmt"
+	"maps"
 	"slices"
 	"strings"
 
@@ -78,6 +79,9 @@ func collectCreateContainerResult(request *CreateContainerRequest) *result {
 	if request.Container.Linux.Resources.Unified == nil {
 		request.Container.Linux.Resources.Unified = map[string]string{}
 	}
+	if request.Container.Linux.Namespaces == nil {
+		request.Container.Linux.Namespaces = []*LinuxNamespace{}
+	}
 
 	return &result{
 		request: resultRequest{
@@ -99,6 +103,7 @@ func collectCreateContainerResult(request *CreateContainerRequest) *result {
 						HugepageLimits: []*HugepageLimit{},
 						Unified:        map[string]string{},
 					},
+					Namespaces: []*LinuxNamespace{},
 				},
 			},
 		},
@@ -227,6 +232,9 @@ func (r *result) adjust(rpl *ContainerAdjustment, plugin string) error {
 		if err := r.adjustSeccompPolicy(rpl.Linux.SeccompPolicy, plugin); err != nil {
 			return err
 		}
+		if err := r.adjustNamespaces(rpl.Linux.Namespaces, plugin); err != nil {
+			return err
+		}
 	}
 	if err := r.adjustRlimits(rpl.Rlimits, plugin); err != nil {
 		return err
@@ -410,6 +418,39 @@ func (r *result) adjustDevices(devices []*LinuxDevice, plugin string) error {
 	return nil
 }
 
+func (r *result) adjustNamespaces(namespaces []*LinuxNamespace, plugin string) error {
+	if len(namespaces) == 0 {
+		return nil
+	}
+
+	create, id := r.request.create, r.request.create.Container.Id
+
+	creatensmap := map[string]*LinuxNamespace{}
+	for _, n := range create.Container.Linux.Namespaces {
+		creatensmap[n.Type] = n
+	}
+
+	for _, n := range namespaces {
+		if n == nil {
+			continue
+		}
+		key, marked := n.IsMarkedForRemoval()
+		if err := r.owners.ClaimNamespace(id, key, plugin); err != nil {
+			return err
+		}
+		if marked {
+			delete(creatensmap, key)
+		} else {
+			creatensmap[key] = n
+		}
+		r.reply.adjust.Linux.Namespaces = append(r.reply.adjust.Linux.Namespaces, n)
+	}
+
+	create.Container.Linux.Namespaces = slices.Collect(maps.Values(creatensmap))
+
+	return nil
+}
+
 func (r *result) adjustCDIDevices(devices []*CDIDevice, plugin string) error {
 	if len(devices) == 0 {
 		return nil

pkg/api/adjustment.go

@@ -147,6 +147,20 @@ func (a *ContainerAdjustment) AddCDIDevice(d *CDIDevice) {
 	a.CDIDevices = append(a.CDIDevices, d) // TODO: should we dup d here ?
 }
 
+// AddOrReplaceNamespace records the addition or replacement of the given namespace to a container.
+func (a *ContainerAdjustment) AddOrReplaceNamespace(n *LinuxNamespace) {
+	a.initLinuxNamespaces()
+	a.Linux.Namespaces = append(a.Linux.Namespaces, n) // TODO: should we dup n here ?
+}
+
+// RemoveNamespace records the removal of the given namespace from a container.
+func (a *ContainerAdjustment) RemoveNamespace(n *LinuxNamespace) {
+	a.initLinuxNamespaces()
+	a.Linux.Namespaces = append(a.Linux.Namespaces, &LinuxNamespace{
+		Type: MarkForRemoval(n.Type),
+	})
+}
+
 // SetLinuxMemoryLimit records setting the memory limit for a container.
 func (a *ContainerAdjustment) SetLinuxMemoryLimit(value int64) {
 	a.initLinuxResourcesMemory()
@@ -323,6 +337,13 @@ func (a *ContainerAdjustment) initLinux() {
 	}
 }
 
+func (a *ContainerAdjustment) initLinuxNamespaces() {
+	a.initLinux()
+	if a.Linux.Namespaces == nil {
+		a.Linux.Namespaces = []*LinuxNamespace{}
+	}
+}
+
 func (a *ContainerAdjustment) initLinuxResources() {
 	a.initLinux()
 	if a.Linux.Resources == nil {