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Enable and configure k8s audit-log (#160)

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* Enable and configure k8s audit-log

* Update coordinator/kubernetes/k8sapi/kubeadm_config.go

Co-authored-by: Malte Poll <mp@edgeless.systems>

* add mount point for audit log dir in kubeadm conf

* Mount audit policy into kube-apiserver static pod

* Write default auditpolicy on cluster init / cluster join

Co-authored-by: Malte Poll <mp@edgeless.systems>
This commit is contained in:
Moritz Eckert 2022-05-20 17:30:37 +02:00 committed by GitHub
parent e4a9be832c
commit 6dc97590fe
6 changed files with 114 additions and 13 deletions
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49
coordinator/kubernetes/k8sapi/kubeadm_config.go
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@ -1,9 +1,12 @@
package k8sapi
import (
"path/filepath"
"github.com/edgelesssys/constellation/coordinator/kubernetes/k8sapi/resources"
"github.com/edgelesssys/constellation/internal/constants"
v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
corev1 "k8s.io/api/core/v1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
kubeletconf "k8s.io/kubelet/config/v1beta1"
kubeadm "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1beta3"
)
@ -13,6 +16,9 @@ import (
const (
bindPort = 6443
auditLogDir = "/var/log/kubernetes/audit/"
auditLogFile = "audit.log"
auditPolicyPath = "/etc/kubernetes/audit-policy.yaml"
)
type CoreOSConfiguration struct{}
@ -24,7 +30,7 @@ func (c *CoreOSConfiguration) InitConfiguration(externalCloudProvider bool) Kube
}
return KubeadmInitYAML{
InitConfiguration: kubeadm.InitConfiguration{
TypeMeta: v1.TypeMeta{
TypeMeta: metav1.TypeMeta{
APIVersion: kubeadm.SchemeGroupVersion.String(),
Kind: "InitConfiguration",
},
@ -41,7 +47,7 @@ func (c *CoreOSConfiguration) InitConfiguration(externalCloudProvider bool) Kube
},
},
ClusterConfiguration: kubeadm.ClusterConfiguration{
TypeMeta: v1.TypeMeta{
TypeMeta: metav1.TypeMeta{
Kind: "ClusterConfiguration",
APIVersion: kubeadm.SchemeGroupVersion.String(),
},
@ -50,6 +56,11 @@ func (c *CoreOSConfiguration) InitConfiguration(externalCloudProvider bool) Kube
APIServer: kubeadm.APIServer{
ControlPlaneComponent: kubeadm.ControlPlaneComponent{
ExtraArgs: map[string]string{
"audit-policy-file": auditPolicyPath,
"audit-log-path": filepath.Join(auditLogDir, auditLogFile), // CIS benchmark
"audit-log-maxage": "30", // CIS benchmark - Default value of Rancher
"audit-log-maxbackup": "10", // CIS benchmark - Default value of Rancher
"audit-log-maxsize": "100", // CIS benchmark - Default value of Rancher
"profiling": "false", // CIS benchmark
"tls-cipher-suites": "TLS_AES_128_GCM_SHA256,TLS_AES_256_GCM_SHA384,TLS_CHACHA20_POLY1305_SHA256," +
"TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256," +
@ -60,6 +71,22 @@ func (c *CoreOSConfiguration) InitConfiguration(externalCloudProvider bool) Kube
"TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,TLS_RSA_WITH_3DES_EDE_CBC_SHA,TLS_RSA_WITH_AES_128_CBC_SHA," +
"TLS_RSA_WITH_AES_128_GCM_SHA256,TLS_RSA_WITH_AES_256_CBC_SHA,TLS_RSA_WITH_AES_256_GCM_SHA384", // CIS benchmark
},
ExtraVolumes: []kubeadm.HostPathMount{
{
Name: "audit-log",
HostPath: auditLogDir,
MountPath: auditLogDir,
ReadOnly: false,
PathType: corev1.HostPathDirectoryOrCreate,
},
{
Name: "audit",
HostPath: auditPolicyPath,
MountPath: auditPolicyPath,
ReadOnly: true,
PathType: corev1.HostPathFile,
},
},
},
CertSANs: []string{"127.0.0.1", "10.118.0.1"},
},
@ -92,7 +119,7 @@ func (c *CoreOSConfiguration) InitConfiguration(externalCloudProvider bool) Kube
"TLS_RSA_WITH_AES_256_GCM_SHA384",
"TLS_RSA_WITH_AES_128_GCM_SHA256",
}, // CIS benchmark
TypeMeta: v1.TypeMeta{
TypeMeta: metav1.TypeMeta{
APIVersion: kubeletconf.SchemeGroupVersion.String(),
Kind: "KubeletConfiguration",
},
@ -107,7 +134,7 @@ func (c *CoreOSConfiguration) JoinConfiguration(externalCloudProvider bool) Kube
}
return KubeadmJoinYAML{
JoinConfiguration: kubeadm.JoinConfiguration{
TypeMeta: v1.TypeMeta{
TypeMeta: metav1.TypeMeta{
APIVersion: kubeadm.SchemeGroupVersion.String(),
Kind: "JoinConfiguration",
},
@ -122,7 +149,7 @@ func (c *CoreOSConfiguration) JoinConfiguration(externalCloudProvider bool) Kube
},
},
KubeletConfiguration: kubeletconf.KubeletConfiguration{
TypeMeta: v1.TypeMeta{
TypeMeta: metav1.TypeMeta{
APIVersion: kubeletconf.SchemeGroupVersion.String(),
Kind: "KubeletConfiguration",
},
@ -135,7 +162,7 @@ type AWSConfiguration struct{}
func (a *AWSConfiguration) InitConfiguration() KubeadmInitYAML {
return KubeadmInitYAML{
InitConfiguration: kubeadm.InitConfiguration{
TypeMeta: v1.TypeMeta{
TypeMeta: metav1.TypeMeta{
APIVersion: kubeadm.SchemeGroupVersion.String(),
Kind: "InitConfiguration",
},
@ -146,7 +173,7 @@ func (a *AWSConfiguration) InitConfiguration() KubeadmInitYAML {
LocalAPIEndpoint: kubeadm.APIEndpoint{BindPort: bindPort},
},
ClusterConfiguration: kubeadm.ClusterConfiguration{
TypeMeta: v1.TypeMeta{
TypeMeta: metav1.TypeMeta{
APIVersion: kubeadm.SchemeGroupVersion.String(),
Kind: "ClusterConfiguration",
},
@ -155,7 +182,7 @@ func (a *AWSConfiguration) InitConfiguration() KubeadmInitYAML {
},
},
KubeletConfiguration: kubeletconf.KubeletConfiguration{
TypeMeta: v1.TypeMeta{
TypeMeta: metav1.TypeMeta{
APIVersion: kubeletconf.SchemeGroupVersion.String(),
Kind: "KubeletConfiguration",
},
@ -166,7 +193,7 @@ func (a *AWSConfiguration) InitConfiguration() KubeadmInitYAML {
func (a *AWSConfiguration) JoinConfiguration() KubeadmJoinYAML {
return KubeadmJoinYAML{
JoinConfiguration: kubeadm.JoinConfiguration{
TypeMeta: v1.TypeMeta{
TypeMeta: metav1.TypeMeta{
APIVersion: kubeadm.SchemeGroupVersion.String(),
Kind: "JoinConfiguration",
},
@ -179,7 +206,7 @@ func (a *AWSConfiguration) JoinConfiguration() KubeadmJoinYAML {
},
},
KubeletConfiguration: kubeletconf.KubeletConfiguration{
TypeMeta: v1.TypeMeta{
TypeMeta: metav1.TypeMeta{
APIVersion: kubeletconf.SchemeGroupVersion.String(),
Kind: "KubeletConfiguration",
},

33
coordinator/kubernetes/k8sapi/resources/auditpolicy.go Normal file
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@ -0,0 +1,33 @@
package resources
import (
v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
auditv1 "k8s.io/apiserver/pkg/apis/audit/v1"
)
// AuditPolicy defines rulesets for what should be logged in the kube-apiserver audit log.
// reference: https://kubernetes.io/docs/tasks/debug/debug-cluster/audit/ .
type AuditPolicy struct {
Policy auditv1.Policy
}
func NewDefaultAuditPolicy() *AuditPolicy {
return &AuditPolicy{
Policy: auditv1.Policy{
TypeMeta: v1.TypeMeta{
APIVersion: "audit.k8s.io/v1",
Kind: "Policy",
},
Rules: []auditv1.PolicyRule{
{
Level: auditv1.LevelMetadata,
},
},
},
}
}
// Marshal marshals the audit policy as a YAML document.
func (p *AuditPolicy) Marshal() ([]byte, error) {
return MarshalK8SResources(p)
}

21
coordinator/kubernetes/k8sapi/resources/auditpolicy_test.go Normal file
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@ -0,0 +1,21 @@
package resources
import (
"testing"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
func TestAuditPolicyMarshalUnmarshal(t *testing.T) {
require := require.New(t)
assert := assert.New(t)
auditPolicy := NewDefaultAuditPolicy()
data, err := auditPolicy.Marshal()
require.NoError(err)
var recreated AuditPolicy
require.NoError(UnmarshalK8SResources(data, &recreated))
assert.Equal(auditPolicy, &recreated)
}

18
coordinator/kubernetes/k8sapi/util.go
View File

@ -37,6 +37,15 @@ type ClusterUtil interface {
type KubernetesUtil struct{}
func (k *KubernetesUtil) InitCluster(initConfig []byte) error {
// TODO: audit policy should be user input
auditPolicy, err := resources.NewDefaultAuditPolicy().Marshal()
if err != nil {
return fmt.Errorf("failed to generate default audit policy: %w", err)
}
if err := os.WriteFile(auditPolicyPath, auditPolicy, 0o644); err != nil {
return fmt.Errorf("failed to write default audit policy: %w", err)
}
initConfigFile, err := os.CreateTemp("", "kubeadm-init.*.yaml")
if err != nil {
return fmt.Errorf("failed to create init config file %v: %w", initConfigFile.Name(), err)
@ -102,6 +111,15 @@ func (k *KubernetesUtil) SetupCloudNodeManager(kubectl Client, cloudNodeManagerC
// JoinCluster joins existing Kubernetes cluster using kubeadm join.
func (k *KubernetesUtil) JoinCluster(joinConfig []byte) error {
// TODO: audit policy should be user input
auditPolicy, err := resources.NewDefaultAuditPolicy().Marshal()
if err != nil {
return fmt.Errorf("failed to generate default audit policy: %w", err)
}
if err := os.WriteFile(auditPolicyPath, auditPolicy, 0o644); err != nil {
return fmt.Errorf("failed to write default audit policy: %w", err)
}
joinConfigFile, err := os.CreateTemp("", "kubeadm-join.*.yaml")
if err != nil {
return fmt.Errorf("failed to create join config file %v: %w", joinConfigFile.Name(), err)

1
go.mod
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@ -208,6 +208,7 @@ require (
google.golang.org/appengine v1.6.7 // indirect
gopkg.in/inf.v0 v0.9.1 // indirect
gopkg.in/yaml.v2 v2.4.0 // indirect
k8s.io/apiserver v0.24.0
k8s.io/cluster-bootstrap v0.0.0 // indirect
k8s.io/component-base v0.24.0 // indirect
k8s.io/kube-openapi v0.0.0-20220328201542-3ee0da9b0b42 // indirect

1
go.sum
View File

@ -2301,6 +2301,7 @@ k8s.io/api v0.24.0/go.mod h1:5Jl90IUrJHUJYEMANRURMiVvJ0g7Ax7r3R1bqO8zx8I=
k8s.io/apiextensions-apiserver v0.24.0/go.mod h1:iuVe4aEpe6827lvO6yWQVxiPSpPoSKVjkq+MIdg84cM=
k8s.io/apimachinery v0.24.0 h1:ydFCyC/DjCvFCHK5OPMKBlxayQytB8pxy8YQInd5UyQ=
k8s.io/apimachinery v0.24.0/go.mod h1:82Bi4sCzVBdpYjyI4jY6aHX+YCUchUIrZrXKedjd2UM=
k8s.io/apiserver v0.24.0 h1:GR7kGsjOMfilRvlG3Stxv/3uz/ryvJ/aZXc5pqdsNV0=
k8s.io/apiserver v0.24.0/go.mod h1:WFx2yiOMawnogNToVvUYT9nn1jaIkMKj41ZYCVycsBA=
k8s.io/cli-runtime v0.24.0 h1:ot3Qf49T852uEyNApABO1UHHpFIckKK/NqpheZYN2gM=
k8s.io/cli-runtime v0.24.0/go.mod h1:9XxoZDsEkRFUThnwqNviqzljtT/LdHtNWvcNFrAXl0A=