PodSecurity: runAsUser

This commit is contained in:
Jordan Liggitt 2021-10-25 13:29:52 -04:00
parent 9b930e3728
commit a476a5e00e
3 changed files with 280 additions and 0 deletions

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/*
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 (
"fmt"
"strings"
corev1 "k8s.io/api/core/v1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/pod-security-admission/api"
)
/*
Containers must not set runAsUser: 0
**Restricted Fields:**
spec.securityContext.runAsUser
spec.containers[*].securityContext.runAsUser
spec.initContainers[*].securityContext.runAsUser
**Allowed Values:**
non-zero values
undefined/null
*/
func init() {
addCheck(CheckRunAsUser)
}
// CheckRunAsUser returns a restricted level check
// that forbides runAsUser=0 in 1.23+
func CheckRunAsUser() Check {
return Check{
ID: "runAsUser",
Level: api.LevelRestricted,
Versions: []VersionedCheck{
{
MinimumVersion: api.MajorMinorVersion(1, 23),
CheckPod: runAsUser_1_23,
},
},
}
}
func runAsUser_1_23(podMetadata *metav1.ObjectMeta, podSpec *corev1.PodSpec) CheckResult {
// things that explicitly set runAsUser=0
var badSetters []string
if podSpec.SecurityContext != nil && podSpec.SecurityContext.RunAsUser != nil && *podSpec.SecurityContext.RunAsUser == 0 {
badSetters = append(badSetters, "pod")
}
// containers that explicitly set runAsUser=0
var explicitlyBadContainers []string
visitContainers(podSpec, func(container *corev1.Container) {
if container.SecurityContext != nil && container.SecurityContext.RunAsUser != nil && *container.SecurityContext.RunAsUser == 0 {
explicitlyBadContainers = append(explicitlyBadContainers, container.Name)
}
})
if len(explicitlyBadContainers) > 0 {
badSetters = append(
badSetters,
fmt.Sprintf(
"%s %s",
pluralize("container", "containers", len(explicitlyBadContainers)),
joinQuote(explicitlyBadContainers),
),
)
}
// pod or containers explicitly set runAsUser=0
if len(badSetters) > 0 {
return CheckResult{
Allowed: false,
ForbiddenReason: "runAsUser=0",
ForbiddenDetail: fmt.Sprintf("%s must not set runAsUser=0", strings.Join(badSetters, " and ")),
}
}
return CheckResult{Allowed: true}
}

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/*
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 TestRunAsUser(t *testing.T) {
tests := []struct {
name string
pod *corev1.Pod
expectAllow bool
expectReason string
expectDetail string
}{
{
name: "pod runAsUser=0",
pod: &corev1.Pod{Spec: corev1.PodSpec{
SecurityContext: &corev1.PodSecurityContext{RunAsUser: utilpointer.Int64(0)},
Containers: []corev1.Container{
{Name: "a", SecurityContext: nil},
},
}},
expectReason: `runAsUser=0`,
expectDetail: `pod must not set runAsUser=0`,
},
{
name: "pod runAsUser=non-zero",
pod: &corev1.Pod{Spec: corev1.PodSpec{
SecurityContext: &corev1.PodSecurityContext{RunAsUser: utilpointer.Int64(1000)},
Containers: []corev1.Container{
{Name: "a", SecurityContext: nil},
},
}},
expectAllow: true,
},
{
name: "pod runAsUser=nil",
pod: &corev1.Pod{Spec: corev1.PodSpec{
SecurityContext: &corev1.PodSecurityContext{RunAsUser: nil},
Containers: []corev1.Container{
{Name: "a", SecurityContext: nil},
},
}},
expectAllow: true,
},
{
name: "containers runAsUser=0",
pod: &corev1.Pod{Spec: corev1.PodSpec{
SecurityContext: &corev1.PodSecurityContext{RunAsUser: utilpointer.Int64(1000)},
Containers: []corev1.Container{
{Name: "a", SecurityContext: nil},
{Name: "b", SecurityContext: &corev1.SecurityContext{}},
{Name: "c", SecurityContext: &corev1.SecurityContext{RunAsUser: utilpointer.Int64(0)}},
{Name: "d", SecurityContext: &corev1.SecurityContext{RunAsUser: utilpointer.Int64(0)}},
{Name: "e", SecurityContext: &corev1.SecurityContext{RunAsUser: utilpointer.Int64(1)}},
{Name: "f", SecurityContext: &corev1.SecurityContext{RunAsUser: utilpointer.Int64(1)}},
},
}},
expectReason: `runAsUser=0`,
expectDetail: `containers "c", "d" must not set runAsUser=0`,
},
{
name: "containers runAsUser=non-zero",
pod: &corev1.Pod{Spec: corev1.PodSpec{
Containers: []corev1.Container{
{Name: "c", SecurityContext: &corev1.SecurityContext{RunAsUser: utilpointer.Int64(1)}},
{Name: "d", SecurityContext: &corev1.SecurityContext{RunAsUser: utilpointer.Int64(2)}},
{Name: "e", SecurityContext: &corev1.SecurityContext{RunAsUser: utilpointer.Int64(3)}},
{Name: "f", SecurityContext: &corev1.SecurityContext{RunAsUser: utilpointer.Int64(4)}},
},
}},
expectAllow: true,
},
}
for _, tc := range tests {
t.Run(tc.name, func(t *testing.T) {
result := runAsUser_1_23(&tc.pod.ObjectMeta, &tc.pod.Spec)
if tc.expectAllow {
if !result.Allowed {
t.Fatalf("expected to be allowed, disallowed: %s, %s", result.ForbiddenReason, result.ForbiddenDetail)
}
return
}
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)
}
})
}
}

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/*
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 test
import (
corev1 "k8s.io/api/core/v1"
"k8s.io/pod-security-admission/api"
"k8s.io/utils/pointer"
)
/*
TODO: include field paths in reflect-based unit test
podFields: []string{
`securityContext.runAsUser`,
},
containerFields: []string{
`securityContext.runAsUser`,
},
*/
func init() {
fixtureData_1_23 := fixtureGenerator{
generatePass: func(p *corev1.Pod) []*corev1.Pod {
p = ensureSecurityContext(p)
return []*corev1.Pod{
tweak(p, func(p *corev1.Pod) {
p.Spec.SecurityContext.RunAsUser = pointer.Int64Ptr(1000)
p.Spec.Containers[0].SecurityContext.RunAsUser = pointer.Int64Ptr(1000)
p.Spec.InitContainers[0].SecurityContext.RunAsUser = pointer.Int64Ptr(1000)
}),
}
},
generateFail: func(p *corev1.Pod) []*corev1.Pod {
p = ensureSecurityContext(p)
return []*corev1.Pod{
// explicit 0 on pod
tweak(p, func(p *corev1.Pod) { p.Spec.SecurityContext.RunAsUser = pointer.Int64Ptr(0) }),
// explicit 0 on containers
tweak(p, func(p *corev1.Pod) { p.Spec.Containers[0].SecurityContext.RunAsUser = pointer.Int64Ptr(0) }),
tweak(p, func(p *corev1.Pod) { p.Spec.InitContainers[0].SecurityContext.RunAsUser = pointer.Int64Ptr(0) }),
}
},
}
registerFixtureGenerator(
fixtureKey{level: api.LevelRestricted, version: api.MajorMinorVersion(1, 23), check: "runAsUser"},
fixtureData_1_23,
)
}