Add init containers to PSP admission

Treat them just like regular containers.

plugin/pkg/admission/security/podsecuritypolicy/admission.go

@@ -186,6 +186,7 @@ func (c *podSecurityPolicyPlugin) Admit(a admission.Attributes) error {
 // the same psp or is not considered valid.
 func assignSecurityContext(provider psp.Provider, pod *api.Pod, fldPath *field.Path) field.ErrorList {
 	generatedSCs := make([]*api.SecurityContext, len(pod.Spec.Containers))
+	var generatedInitSCs []*api.SecurityContext
 
 	errs := field.ErrorList{}
 
@@ -201,6 +202,26 @@ func assignSecurityContext(provider psp.Provider, pod *api.Pod, fldPath *field.P
 	pod.Spec.SecurityContext = psc
 	errs = append(errs, provider.ValidatePodSecurityContext(pod, field.NewPath("spec", "securityContext"))...)
 
+	// Note: this is not changing the original container, we will set container SCs later so long
+	// as all containers validated under the same PSP.
+	for i, containerCopy := range pod.Spec.InitContainers {
+		// We will determine the effective security context for the container and validate against that
+		// since that is how the sc provider will eventually apply settings in the runtime.
+		// This results in an SC that is based on the Pod's PSC with the set fields from the container
+		// overriding pod level settings.
+		containerCopy.SecurityContext = sc.DetermineEffectiveSecurityContext(pod, &containerCopy)
+
+		sc, err := provider.CreateContainerSecurityContext(pod, &containerCopy)
+		if err != nil {
+			errs = append(errs, field.Invalid(field.NewPath("spec", "initContainers").Index(i).Child("securityContext"), "", err.Error()))
+			continue
+		}
+		generatedInitSCs = append(generatedInitSCs, sc)
+
+		containerCopy.SecurityContext = sc
+		errs = append(errs, provider.ValidateContainerSecurityContext(pod, &containerCopy, field.NewPath("spec", "initContainers").Index(i).Child("securityContext"))...)
+	}
+
 	// Note: this is not changing the original container, we will set container SCs later so long
 	// as all containers validated under the same PSP.
 	for i, containerCopy := range pod.Spec.Containers {
@@ -229,6 +250,9 @@ func assignSecurityContext(provider psp.Provider, pod *api.Pod, fldPath *field.P
 
 	// if we've reached this code then we've generated and validated an SC for every container in the
 	// pod so let's apply what we generated.  Note: the psc is already applied.
+	for i, sc := range generatedInitSCs {
+		pod.Spec.InitContainers[i].SecurityContext = sc
+	}
 	for i, sc := range generatedSCs {
 		pod.Spec.Containers[i].SecurityContext = sc
 	}

plugin/pkg/admission/security/podsecuritypolicy/admission_test.go

@@ -44,6 +44,12 @@ func NewTestAdmission(store cache.Store, kclient clientset.Interface) kadmission
 	}
 }
 
+func useInitContainers(pod *kapi.Pod) *kapi.Pod {
+	pod.Spec.InitContainers = pod.Spec.Containers
+	pod.Spec.Containers = []kapi.Container{}
+	return pod
+}
+
 func TestAdmitPrivileged(t *testing.T) {
 	createPodWithPriv := func(priv bool) *kapi.Pod {
 		pod := goodPod()
@@ -203,6 +209,18 @@ func TestAdmitCaps(t *testing.T) {
 			}
 		}
 	}
+
+	for k, v := range tc {
+		useInitContainers(v.pod)
+		testPSPAdmit(k, v.psps, v.pod, v.shouldPass, v.expectedPSP, t)
+
+		if v.expectedCapabilities != nil {
+			if !reflect.DeepEqual(v.expectedCapabilities, v.pod.Spec.InitContainers[0].SecurityContext.Capabilities) {
+				t.Errorf("%s resulted in caps that were not expected - expected: %v, received: %v", k, v.expectedCapabilities, v.pod.Spec.InitContainers[0].SecurityContext.Capabilities)
+			}
+		}
+	}
+
 }
 
 func TestAdmitVolumes(t *testing.T) {
@@ -235,6 +253,10 @@ func TestAdmitVolumes(t *testing.T) {
 		// expect a denial for this PSP
 		testPSPAdmit(fmt.Sprintf("%s denial", string(fsType)), []*extensions.PodSecurityPolicy{psp}, pod, false, "", t)
 
+		// also expect a denial for this PSP if it's an init container
+		useInitContainers(pod)
+		testPSPAdmit(fmt.Sprintf("%s denial", string(fsType)), []*extensions.PodSecurityPolicy{psp}, pod, false, "", t)
+
 		// now add the fstype directly to the psp and it should validate
 		psp.Spec.Volumes = []extensions.FSType{fsType}
 		testPSPAdmit(fmt.Sprintf("%s direct accept", string(fsType)), []*extensions.PodSecurityPolicy{psp}, pod, true, psp.Name, t)
@@ -304,6 +326,18 @@ func TestAdmitHostNetwork(t *testing.T) {
 			}
 		}
 	}
+
+	// test again with init containers
+	for k, v := range tests {
+		useInitContainers(v.pod)
+		testPSPAdmit(k, v.psps, v.pod, v.shouldPass, v.expectedPSP, t)
+
+		if v.shouldPass {
+			if v.pod.Spec.SecurityContext.HostNetwork != v.expectedHostNetwork {
+				t.Errorf("%s expected hostNetwork to be %t", k, v.expectedHostNetwork)
+			}
+		}
+	}
 }
 
 func TestAdmitHostPorts(t *testing.T) {