PodSecurity: hostPorts: cleanup

Reformat message
Add unit test to exercise message/details

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

@@ -18,6 +18,8 @@ package policy
 
 import (
 	"fmt"
+	"strconv"
+	"strings"
 
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -26,6 +28,17 @@ import (
 	"k8s.io/pod-security-admission/api"
 )
 
+/*
+HostPort ports must be forbidden.
+
+**Restricted Fields:**
+
+spec.containers[*].ports[*].hostPort
+spec.initContainers[*].ports[*].hostPort
+
+**Allowed Values:** undefined/0
+*/
+
 func init() {
 	addCheck(CheckHostPorts)
 }
@@ -46,25 +59,32 @@ func CheckHostPorts() Check {
 }
 
 func hostPorts_1_0(podMetadata *metav1.ObjectMeta, podSpec *corev1.PodSpec) CheckResult {
-	forbiddenContainers := sets.NewString()
-	forbiddenHostPorts := sets.NewInt32()
+	var badContainers []string
+	forbiddenHostPorts := sets.NewString()
 	visitContainersWithPath(podSpec, field.NewPath("spec"), func(container *corev1.Container, path *field.Path) {
+		valid := true
 		for _, c := range container.Ports {
 			if c.HostPort != 0 {
-				forbiddenContainers.Insert(container.Name)
-				forbiddenHostPorts.Insert(c.HostPort)
+				valid = false
+				forbiddenHostPorts.Insert(strconv.Itoa(int(c.HostPort)))
 			}
 		}
+		if !valid {
+			badContainers = append(badContainers, container.Name)
+		}
 	})
 
-	if len(forbiddenHostPorts) > 0 {
+	if len(badContainers) > 0 {
 		return CheckResult{
 			Allowed:         false,
-			ForbiddenReason: "forbidden host ports",
+			ForbiddenReason: "hostPort",
 			ForbiddenDetail: fmt.Sprintf(
-				"containers %q use these host ports %d",
-				forbiddenContainers.List(),
-				forbiddenHostPorts.List(),
+				"%s %s %s %s %s",
+				pluralize("container", "containers", len(badContainers)),
+				joinQuote(badContainers),
+				pluralize("uses", "use", len(badContainers)),
+				pluralize("hostPort", "hostPorts", len(forbiddenHostPorts)),
+				strings.Join(forbiddenHostPorts.List(), ", "),
 			),
 		}
 	}

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

@@ -0,0 +1,71 @@
+/*
+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"
+)
+
+func TestHostPort(t *testing.T) {
+	tests := []struct {
+		name         string
+		pod          *corev1.Pod
+		expectReason string
+		expectDetail string
+	}{
+		{
+			name: "one container, one host port",
+			pod: &corev1.Pod{Spec: corev1.PodSpec{
+				Containers: []corev1.Container{
+					{Name: "a", Ports: []corev1.ContainerPort{{HostPort: 0}}},
+					{Name: "b", Ports: []corev1.ContainerPort{{HostPort: 0}, {HostPort: 20}}},
+				},
+			}},
+			expectReason: `hostPort`,
+			expectDetail: `container "b" uses hostPort 20`,
+		},
+		{
+			name: "multiple containers, multiple host port",
+			pod: &corev1.Pod{Spec: corev1.PodSpec{
+				Containers: []corev1.Container{
+					{Name: "a", Ports: []corev1.ContainerPort{{HostPort: 0}}},
+					{Name: "b", Ports: []corev1.ContainerPort{{HostPort: 0}, {HostPort: 10}, {HostPort: 20}}},
+					{Name: "c", Ports: []corev1.ContainerPort{{HostPort: 0}, {HostPort: 10}, {HostPort: 30}}},
+				},
+			}},
+			expectReason: `hostPort`,
+			expectDetail: `containers "b", "c" use hostPorts 10, 20, 30`,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			result := hostPorts_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_hostPorts.go

@@ -31,7 +31,7 @@ containerFields: []string{
 
 func init() {
 	fixtureData_1_0 := fixtureGenerator{
-		expectErrorSubstring: "forbidden host ports",
+		expectErrorSubstring: "hostPort",
 		generatePass: func(p *corev1.Pod) []*corev1.Pod {
 			return []*corev1.Pod{
 				// no host ports
@@ -60,6 +60,7 @@ func init() {
 						},
 					}
 				}),
+				// check initContainer
 				tweak(p, func(p *corev1.Pod) {
 					p.Spec.InitContainers[0].Ports = []corev1.ContainerPort{
 						{
@@ -68,7 +69,7 @@ func init() {
 						},
 					}
 				}),
-				// both init-container and app container use host ports and regular ports
+				// mix of hostPorts and regular ports
 				tweak(p, func(p *corev1.Pod) {
 					p.Spec.Containers[0].Ports = []corev1.ContainerPort{
 						{