PodSecurity: windowsHostProcess: cleanup

Rename to windowsHostProcess
Format reason/details
Add unit tests

staging/src/k8s.io/pod-security-admission/policy/check_windowsHostProcess.go

@@ -17,6 +17,7 @@ limitations under the License.
 package policy
 
 import (
+	"fmt"
 	"strings"
 
 	corev1 "k8s.io/api/core/v1"
@@ -26,43 +27,44 @@ import (
 )
 
 /*
-Containers must not run as hostProcess.
+Pod and containers must not set securityContext.windowsOptions.hostProcess to true.
 
 **Restricted Fields:**
 
 spec.securityContext.windowsOptions.hostProcess
 spec.containers[*].securityContext.windowsOptions.hostProcess
+spec.initContainers[*].securityContext.windowsOptions.hostProcess
 
 **Allowed Values:** undefined / false
 */
 
 func init() {
-	addCheck(CheckHostProcess)
+	addCheck(CheckWindowsHostProcess)
 }
 
-// CheckHostProcess returns a baseline level check
+// CheckWindowsHostProcess returns a baseline level check
 // that forbids hostProcess=true in 1.0+
-func CheckHostProcess() Check {
+func CheckWindowsHostProcess() Check {
 	return Check{
-		ID:    "hostProcess",
+		ID:    "windowsHostProcess",
 		Level: api.LevelBaseline,
 		Versions: []VersionedCheck{
 			{
 				MinimumVersion: api.MajorMinorVersion(1, 0),
-				CheckPod:       hostProcess_1_0,
+				CheckPod:       windowsHostProcess_1_0,
 			},
 		},
 	}
 }
 
-func hostProcess_1_0(podMetadata *metav1.ObjectMeta, podSpec *corev1.PodSpec) CheckResult {
+func windowsHostProcess_1_0(podMetadata *metav1.ObjectMeta, podSpec *corev1.PodSpec) CheckResult {
-	var forbiddenContainers []string
+	var badContainers []string
 	visitContainersWithPath(podSpec, field.NewPath("spec"), func(container *corev1.Container, path *field.Path) {
 		if container.SecurityContext != nil &&
 			container.SecurityContext.WindowsOptions != nil &&
 			container.SecurityContext.WindowsOptions.HostProcess != nil &&
 			*container.SecurityContext.WindowsOptions.HostProcess {
-			forbiddenContainers = append(forbiddenContainers, container.Name)
+			badContainers = append(badContainers, container.Name)
 		}
 	})
 
@@ -75,11 +77,25 @@ func hostProcess_1_0(podMetadata *metav1.ObjectMeta, podSpec *corev1.PodSpec) Ch
 	}
 
 	// pod or containers explicitly set hostProcess=true
-	if len(forbiddenContainers) > 0 || podSpecForbidden {
+	var forbiddenSetters []string
+	if podSpecForbidden {
+		forbiddenSetters = append(forbiddenSetters, "pod")
+	}
+	if len(badContainers) > 0 {
+		forbiddenSetters = append(
+			forbiddenSetters,
+			fmt.Sprintf(
+				"%s %s",
+				pluralize("container", "containers", len(badContainers)),
+				joinQuote(badContainers),
+			),
+		)
+	}
+	if len(forbiddenSetters) > 0 {
 		return CheckResult{
 			Allowed:         false,
-			ForbiddenReason: "hostProcess == true",
+			ForbiddenReason: "hostProcess",
-			ForbiddenDetail: strings.Join(forbiddenContainers, ", "),
+			ForbiddenDetail: fmt.Sprintf("%s must not set securityContext.windowsOptions.hostProcess=true", strings.Join(forbiddenSetters, " and ")),
 		}
 	}
 

staging/src/k8s.io/pod-security-admission/policy/check_windowsHostProcess_test.go

@@ -0,0 +1,67 @@
+/*
+Copyright 2021 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package policy
+
+import (
+	"testing"
+
+	corev1 "k8s.io/api/core/v1"
+	utilpointer "k8s.io/utils/pointer"
+)
+
+func TestWindowsHostProcess(t *testing.T) {
+	tests := []struct {
+		name         string
+		pod          *corev1.Pod
+		expectReason string
+		expectDetail string
+	}{
+		{
+			name: "host process",
+			pod: &corev1.Pod{Spec: corev1.PodSpec{
+				SecurityContext: &corev1.PodSecurityContext{
+					WindowsOptions: &corev1.WindowsSecurityContextOptions{HostProcess: utilpointer.Bool(true)},
+				},
+				Containers: []corev1.Container{
+					{Name: "a", SecurityContext: nil},
+					{Name: "b", SecurityContext: &corev1.SecurityContext{}},
+					{Name: "c", SecurityContext: &corev1.SecurityContext{WindowsOptions: &corev1.WindowsSecurityContextOptions{}}},
+					{Name: "d", SecurityContext: &corev1.SecurityContext{WindowsOptions: &corev1.WindowsSecurityContextOptions{HostProcess: utilpointer.Bool(false)}}},
+					{Name: "e", SecurityContext: &corev1.SecurityContext{WindowsOptions: &corev1.WindowsSecurityContextOptions{HostProcess: utilpointer.Bool(true)}}},
+					{Name: "f", SecurityContext: &corev1.SecurityContext{WindowsOptions: &corev1.WindowsSecurityContextOptions{HostProcess: utilpointer.Bool(true)}}},
+				},
+			}},
+			expectReason: `hostProcess`,
+			expectDetail: `pod and containers "e", "f" must not set securityContext.windowsOptions.hostProcess=true`,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			result := windowsHostProcess_1_0(&tc.pod.ObjectMeta, &tc.pod.Spec)
+			if result.Allowed {
+				t.Fatal("expected disallowed")
+			}
+			if e, a := tc.expectReason, result.ForbiddenReason; e != a {
+				t.Errorf("expected\n%s\ngot\n%s", e, a)
+			}
+			if e, a := tc.expectDetail, result.ForbiddenDetail; e != a {
+				t.Errorf("expected\n%s\ngot\n%s", e, a)
+			}
+		})
+	}
+}

staging/src/k8s.io/pod-security-admission/test/fixtures_windowsHostProcess.go

@@ -42,6 +42,7 @@ func init() {
 			// minimal valid pod already captures all valid combinations
 			return nil
 		},
+		expectErrorSubstring: "hostProcess",
 		failRequiresFeatures: []featuregate.Feature{"WindowsHostProcessContainers"},
 		generateFail: func(p *corev1.Pod) []*corev1.Pod {
 			p = ensureSecurityContext(p)
@@ -75,7 +76,7 @@ func init() {
 	}
 
 	registerFixtureGenerator(
-		fixtureKey{level: api.LevelBaseline, version: api.MajorMinorVersion(1, 0), check: "hostProcess"},
+		fixtureKey{level: api.LevelBaseline, version: api.MajorMinorVersion(1, 0), check: "windowsHostProcess"},
 		fixtureData_1_0,
 	)
 	// TODO: register another set of fixtures with passing test cases that explicitly set hostProcess=false at pod and container level once hostProcess is GA