PodSecurity: check: selinux

Co-authored-by: Tim Allclair <timallclair@gmail.com>
This commit is contained in:
Jordan Liggitt 2021-06-22 14:11:38 -04:00
parent 42dc070b47
commit 12ea930aae
2 changed files with 208 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 (
"strings"
corev1 "k8s.io/api/core/v1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/util/sets"
"k8s.io/apimachinery/pkg/util/validation/field"
"k8s.io/pod-security-admission/api"
)
/*
Setting the SELinux type is restricted, and setting a custom SELinux user or role option is forbidden.
**Restricted Fields:**
spec.securityContext.seLinuxOptions.type
spec.containers[*].securityContext.seLinuxOptions.type
spec.initContainers[*].securityContext.seLinuxOptions.type
**Allowed Values:**
undefined/empty
container_t
container_init_t
container_kvm_t
**Restricted Fields:**
spec.securityContext.seLinuxOptions.user
spec.containers[*].securityContext.seLinuxOptions.user
spec.initContainers[*].securityContext.seLinuxOptions.user
spec.securityContext.seLinuxOptions.role
spec.containers[*].securityContext.seLinuxOptions.role
spec.initContainers[*].securityContext.seLinuxOptions.role
**Allowed Values:** undefined/empty
*/
func init() {
addCheck(CheckSELinux)
}
// CheckSELinux returns a baseline level check
// that limits seLinuxOptions type, user, and role values in 1.0+
func CheckSELinux() Check {
return Check{
ID: "selinux",
Level: api.LevelBaseline,
Versions: []VersionedCheck{
{
MinimumVersion: api.MajorMinorVersion(1, 0),
CheckPod: checkSelinux_1_0,
},
},
}
}
var (
selinux_allowed_types_1_0 = sets.NewString("", "container_t", "container_init_t", "container_kvm_t")
)
func checkSelinux_1_0(podMetadata *metav1.ObjectMeta, podSpec *corev1.PodSpec) CheckResult {
var forbiddenDetails []string
checkSelinuxOptions := func(path *field.Path, opts *corev1.SELinuxOptions) {
if !selinux_allowed_types_1_0.Has(opts.Type) {
forbiddenDetails = append(forbiddenDetails, path.Child("securityContext", "seLinuxOptions", "type").String())
}
if len(opts.User) > 0 {
forbiddenDetails = append(forbiddenDetails, path.Child("securityContext", "seLinuxOptions", "user").String())
}
if len(opts.Role) > 0 {
forbiddenDetails = append(forbiddenDetails, path.Child("securityContext", "seLinuxOptions", "role").String())
}
}
if podSpec.SecurityContext != nil && podSpec.SecurityContext.SELinuxOptions != nil {
checkSelinuxOptions(field.NewPath("spec"), podSpec.SecurityContext.SELinuxOptions)
}
visitContainersWithPath(podSpec, field.NewPath("spec"), func(container *corev1.Container, path *field.Path) {
if container.SecurityContext != nil && container.SecurityContext.SELinuxOptions != nil {
checkSelinuxOptions(path, container.SecurityContext.SELinuxOptions)
}
})
if len(forbiddenDetails) > 0 {
return CheckResult{
Allowed: false,
ForbiddenReason: "forbidden seLinuxOptions",
ForbiddenDetail: strings.Join(forbiddenDetails, ", "),
}
}
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 test
import (
corev1 "k8s.io/api/core/v1"
"k8s.io/pod-security-admission/api"
)
/*
TODO: include field paths in reflect-based unit test
podFields: []string{
`spec.securityContext.seLinuxOptions.type`,
`spec.securityContext.seLinuxOptions.user`,
`spec.securityContext.seLinuxOptions.role`,
},
containerFields: []string{
`securityContext.seLinuxOptions.type`,
`securityContext.seLinuxOptions.user`,
`securityContext.seLinuxOptions.role`,
},
*/
func init() {
fixtureData_1_0 := fixtureGenerator{
expectErrorSubstring: "seLinuxOptions",
generatePass: func(p *corev1.Pod) []*corev1.Pod {
p = ensureSELinuxOptions(p)
return []*corev1.Pod{
// security context with no seLinuxOptions
tweak(p, func(p *corev1.Pod) { p.Spec.SecurityContext.SELinuxOptions = nil }),
tweak(p, func(p *corev1.Pod) { p.Spec.Containers[0].SecurityContext.SELinuxOptions = nil }),
tweak(p, func(p *corev1.Pod) { p.Spec.InitContainers[0].SecurityContext.SELinuxOptions = nil }),
// seLinuxOptions with type=""
tweak(p, func(p *corev1.Pod) { p.Spec.SecurityContext.SELinuxOptions.Type = "" }),
tweak(p, func(p *corev1.Pod) { p.Spec.Containers[0].SecurityContext.SELinuxOptions.Type = "" }),
tweak(p, func(p *corev1.Pod) { p.Spec.InitContainers[0].SecurityContext.SELinuxOptions.Type = "" }),
// seLinuxOptions with type="container_t"
tweak(p, func(p *corev1.Pod) { p.Spec.SecurityContext.SELinuxOptions.Type = "container_t" }),
tweak(p, func(p *corev1.Pod) { p.Spec.Containers[0].SecurityContext.SELinuxOptions.Type = "container_t" }),
tweak(p, func(p *corev1.Pod) { p.Spec.InitContainers[0].SecurityContext.SELinuxOptions.Type = "container_t" }),
// seLinuxOptions with type="container_init_t"
tweak(p, func(p *corev1.Pod) { p.Spec.SecurityContext.SELinuxOptions.Type = "container_init_t" }),
tweak(p, func(p *corev1.Pod) { p.Spec.Containers[0].SecurityContext.SELinuxOptions.Type = "container_init_t" }),
tweak(p, func(p *corev1.Pod) { p.Spec.InitContainers[0].SecurityContext.SELinuxOptions.Type = "container_init_t" }),
// seLinuxOptions with type="container_kvm_t"
tweak(p, func(p *corev1.Pod) { p.Spec.SecurityContext.SELinuxOptions.Type = "container_kvm_t" }),
tweak(p, func(p *corev1.Pod) { p.Spec.Containers[0].SecurityContext.SELinuxOptions.Type = "container_kvm_t" }),
tweak(p, func(p *corev1.Pod) { p.Spec.InitContainers[0].SecurityContext.SELinuxOptions.Type = "container_kvm_t" }),
// seLinuxOptions with level=""
tweak(p, func(p *corev1.Pod) { p.Spec.SecurityContext.SELinuxOptions.Level = "" }),
tweak(p, func(p *corev1.Pod) { p.Spec.Containers[0].SecurityContext.SELinuxOptions.Level = "" }),
tweak(p, func(p *corev1.Pod) { p.Spec.InitContainers[0].SecurityContext.SELinuxOptions.Level = "" }),
// seLinuxOptions with arbitrary level=""
tweak(p, func(p *corev1.Pod) { p.Spec.SecurityContext.SELinuxOptions.Level = "somevalue" }),
tweak(p, func(p *corev1.Pod) { p.Spec.Containers[0].SecurityContext.SELinuxOptions.Level = "somevalue" }),
tweak(p, func(p *corev1.Pod) { p.Spec.InitContainers[0].SecurityContext.SELinuxOptions.Level = "somevalue" }),
}
},
generateFail: func(p *corev1.Pod) []*corev1.Pod {
p = ensureSELinuxOptions(p)
return []*corev1.Pod{
// seLinuxOptions with out of bounds type
tweak(p, func(p *corev1.Pod) { p.Spec.SecurityContext.SELinuxOptions.Type = "somevalue" }),
tweak(p, func(p *corev1.Pod) { p.Spec.Containers[0].SecurityContext.SELinuxOptions.Type = "somevalue" }),
tweak(p, func(p *corev1.Pod) { p.Spec.InitContainers[0].SecurityContext.SELinuxOptions.Type = "somevalue" }),
// seLinuxOptions with out of bounds user
tweak(p, func(p *corev1.Pod) { p.Spec.SecurityContext.SELinuxOptions.User = "somevalue" }),
tweak(p, func(p *corev1.Pod) { p.Spec.Containers[0].SecurityContext.SELinuxOptions.User = "somevalue" }),
tweak(p, func(p *corev1.Pod) { p.Spec.InitContainers[0].SecurityContext.SELinuxOptions.User = "somevalue" }),
// seLinuxOptions with out of bounds role
tweak(p, func(p *corev1.Pod) { p.Spec.SecurityContext.SELinuxOptions.Role = "somevalue" }),
tweak(p, func(p *corev1.Pod) { p.Spec.Containers[0].SecurityContext.SELinuxOptions.Role = "somevalue" }),
tweak(p, func(p *corev1.Pod) { p.Spec.InitContainers[0].SecurityContext.SELinuxOptions.Role = "somevalue" }),
}
},
}
registerFixtureGenerator(
fixtureKey{level: api.LevelBaseline, version: api.MajorMinorVersion(1, 0), check: "selinux"},
fixtureData_1_0,
)
}