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PodSecurity: check: addCapabilities
This commit is contained in:
Jordan Liggitt
parent
3733e209c9
commit
93c6f8969a
@ -0,0 +1,92 @@
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/*
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Copyright 2021 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package policy
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import (
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"fmt"
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corev1 "k8s.io/api/core/v1"
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metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
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"k8s.io/apimachinery/pkg/util/sets"
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"k8s.io/apimachinery/pkg/util/validation/field"
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"k8s.io/pod-security-admission/api"
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)
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func init() {
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addCheck(CheckAddCapabilities)
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}
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// CheckAddCapabilities returns a baseline level check
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// that limits the capabilities that can be added in 1.0+
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func CheckAddCapabilities() Check {
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return Check{
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ID: "addCapabilities",
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Level: api.LevelBaseline,
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Versions: []VersionedCheck{
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{
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MinimumVersion: api.MajorMinorVersion(1, 0),
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CheckPod: addCapabilities_1_0,
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},
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},
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}
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}
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var (
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capabilities_allowed_1_0 = sets.NewString(
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"AUDIT_WRITE",
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"CHOWN",
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"DAC_OVERRIDE",
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"FOWNER",
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"FSETID",
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"KILL",
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"MKNOD",
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"NET_BIND_SERVICE",
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"SETFCAP",
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"SETGID",
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"SETPCAP",
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"SETUID",
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"SYS_CHROOT",
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)
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)
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func addCapabilities_1_0(podMetadata *metav1.ObjectMeta, podSpec *corev1.PodSpec) CheckResult {
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forbiddenContainers := sets.NewString()
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forbiddenCapabilities := sets.NewString()
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visitContainersWithPath(podSpec, field.NewPath("spec"), func(container *corev1.Container, path *field.Path) {
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if container.SecurityContext != nil && container.SecurityContext.Capabilities != nil {
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for _, c := range container.SecurityContext.Capabilities.Add {
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if !capabilities_allowed_1_0.Has(string(c)) {
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forbiddenContainers.Insert(container.Name)
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forbiddenCapabilities.Insert(string(c))
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}
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}
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}
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})
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if len(forbiddenCapabilities) > 0 {
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return CheckResult{
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Allowed: false,
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ForbiddenReason: "forbidden capabilities",
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ForbiddenDetail: fmt.Sprintf(
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"containers %q added %q",
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forbiddenContainers.List(),
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forbiddenCapabilities.List(),
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),
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}
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}
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return CheckResult{Allowed: true}
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}
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@ -0,0 +1,106 @@
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/*
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Copyright 2021 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package test
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import (
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corev1 "k8s.io/api/core/v1"
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"k8s.io/pod-security-admission/api"
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)
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/*
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TODO: include field paths in reflect-based unit test
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containerFields: []string{
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`securityContext.capabilities.add`,
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},
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*/
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// ensureCapabilities ensures the pod and all initContainers and containers have a non-nil capabilities.
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func ensureCapabilities(p *corev1.Pod) *corev1.Pod {
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p = ensureSecurityContext(p)
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for i := range p.Spec.Containers {
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if p.Spec.Containers[i].SecurityContext.Capabilities == nil {
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p.Spec.Containers[i].SecurityContext.Capabilities = &corev1.Capabilities{}
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}
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}
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for i := range p.Spec.InitContainers {
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if p.Spec.InitContainers[i].SecurityContext.Capabilities == nil {
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p.Spec.InitContainers[i].SecurityContext.Capabilities = &corev1.Capabilities{}
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}
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}
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return p
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}
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func init() {
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fixtureData_1_0 := fixtureGenerator{
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expectErrorSubstring: "forbidden capabilities",
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generatePass: func(p *corev1.Pod) []*corev1.Pod {
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p = ensureCapabilities(p)
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return []*corev1.Pod{
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// all allowed capabilities
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tweak(p, func(p *corev1.Pod) {
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p.Spec.Containers[0].SecurityContext.Capabilities.Add = []corev1.Capability{
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"AUDIT_WRITE", "CHOWN", "DAC_OVERRIDE", "FOWNER", "FSETID", "KILL", "MKNOD", "NET_BIND_SERVICE", "SETFCAP", "SETGID", "SETPCAP", "SETUID", "SYS_CHROOT",
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}
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}),
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tweak(p, func(p *corev1.Pod) {
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p.Spec.InitContainers[0].SecurityContext.Capabilities.Add = []corev1.Capability{
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"AUDIT_WRITE", "CHOWN", "DAC_OVERRIDE", "FOWNER", "FSETID", "KILL", "MKNOD", "NET_BIND_SERVICE", "SETFCAP", "SETGID", "SETPCAP", "SETUID", "SYS_CHROOT",
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}
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}),
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}
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},
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generateFail: func(p *corev1.Pod) []*corev1.Pod {
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p = ensureCapabilities(p)
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return []*corev1.Pod{
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// NET_RAW
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tweak(p, func(p *corev1.Pod) {
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p.Spec.Containers[0].SecurityContext.Capabilities.Add = []corev1.Capability{"NET_RAW"}
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}),
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tweak(p, func(p *corev1.Pod) {
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p.Spec.InitContainers[0].SecurityContext.Capabilities.Add = []corev1.Capability{"NET_RAW"}
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}),
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// case-difference
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tweak(p, func(p *corev1.Pod) {
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p.Spec.Containers[0].SecurityContext.Capabilities.Add = []corev1.Capability{"chown"}
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}),
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tweak(p, func(p *corev1.Pod) {
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p.Spec.InitContainers[0].SecurityContext.Capabilities.Add = []corev1.Capability{"chown"}
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}),
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// unknown capability
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tweak(p, func(p *corev1.Pod) {
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p.Spec.Containers[0].SecurityContext.Capabilities.Add = []corev1.Capability{"bogus"}
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}),
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tweak(p, func(p *corev1.Pod) {
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p.Spec.InitContainers[0].SecurityContext.Capabilities.Add = []corev1.Capability{"bogus"}
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}),
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// CAP_ prefix
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tweak(p, func(p *corev1.Pod) {
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p.Spec.Containers[0].SecurityContext.Capabilities.Add = []corev1.Capability{"CAP_CHOWN"}
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}),
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tweak(p, func(p *corev1.Pod) {
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p.Spec.InitContainers[0].SecurityContext.Capabilities.Add = []corev1.Capability{"CAP_CHOWN"}
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}),
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}
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},
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}
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registerFixtureGenerator(
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fixtureKey{level: api.LevelBaseline, version: api.MajorMinorVersion(1, 0), check: "addCapabilities"},
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fixtureData_1_0,
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)
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}
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