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modify the signing/approving controller to tolerate either set of usa…
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…ges for kubelet client and serving certificates

Signed-off-by: Paco Xu <paco.xu@daocloud.io>
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@pacoxu
pacoxu committed Aug 2, 2022
1 parent b0d5769 commit e6176c2
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Showing 7 changed files with 191 additions and 39 deletions.
60 changes: 42 additions & 18 deletions pkg/apis/certificates/helpers.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -50,16 +50,22 @@ var (
uriSANNotAllowedErr = fmt.Errorf("URI subjectAltNames are not allowed")
)

var kubeletServingRequiredUsages = sets.NewString(
string(UsageDigitalSignature),
string(UsageKeyEncipherment),
string(UsageServerAuth),
var (
kubeletServingRequiredUsages = sets.NewString(
string(UsageDigitalSignature),
string(UsageKeyEncipherment),
string(UsageServerAuth),
)
kubeletServingRequiredUsagesNoRSA = sets.NewString(
string(UsageDigitalSignature),
string(UsageServerAuth),
)
)

func IsKubeletServingCSR(req *x509.CertificateRequest, usages sets.String) bool {
return ValidateKubeletServingCSR(req, usages) == nil
func IsKubeletServingCSR(req *x509.CertificateRequest, usages sets.String, allowOmittingUsageKeyEncipherment bool) bool {
return ValidateKubeletServingCSR(req, usages, allowOmittingUsageKeyEncipherment) == nil
}
func ValidateKubeletServingCSR(req *x509.CertificateRequest, usages sets.String) error {
func ValidateKubeletServingCSR(req *x509.CertificateRequest, usages sets.String, allowOmittingUsageKeyEncipherment bool) error {
if !reflect.DeepEqual([]string{"system:nodes"}, req.Subject.Organization) {
return organizationNotSystemNodesErr
}
Expand All @@ -76,8 +82,14 @@ func ValidateKubeletServingCSR(req *x509.CertificateRequest, usages sets.String)
return uriSANNotAllowedErr
}

if !kubeletServingRequiredUsages.Equal(usages) {
return fmt.Errorf("usages did not match %v", kubeletServingRequiredUsages.List())
if allowOmittingUsageKeyEncipherment {
if !kubeletServingRequiredUsages.Equal(usages) && !kubeletServingRequiredUsagesNoRSA.Equal(usages) {
return fmt.Errorf("usages did not match %v", kubeletServingRequiredUsages.List())
}
} else {
if !kubeletServingRequiredUsages.Equal(usages) {
return fmt.Errorf("usages did not match %v", kubeletServingRequiredUsages.List())
}
}

if !strings.HasPrefix(req.Subject.CommonName, "system:node:") {
Expand All @@ -87,16 +99,22 @@ func ValidateKubeletServingCSR(req *x509.CertificateRequest, usages sets.String)
return nil
}

var kubeletClientRequiredUsages = sets.NewString(
string(UsageDigitalSignature),
string(UsageKeyEncipherment),
string(UsageClientAuth),
var (
kubeletClientRequiredUsagesNoRSA = sets.NewString(
string(UsageDigitalSignature),
string(UsageClientAuth),
)
kubeletClientRequiredUsages = sets.NewString(
string(UsageDigitalSignature),
string(UsageKeyEncipherment),
string(UsageClientAuth),
)
)

func IsKubeletClientCSR(req *x509.CertificateRequest, usages sets.String) bool {
return ValidateKubeletClientCSR(req, usages) == nil
func IsKubeletClientCSR(req *x509.CertificateRequest, usages sets.String, allowOmittingUsageKeyEncipherment bool) bool {
return ValidateKubeletClientCSR(req, usages, allowOmittingUsageKeyEncipherment) == nil
}
func ValidateKubeletClientCSR(req *x509.CertificateRequest, usages sets.String) error {
func ValidateKubeletClientCSR(req *x509.CertificateRequest, usages sets.String, allowOmittingUsageKeyEncipherment bool) error {
if !reflect.DeepEqual([]string{"system:nodes"}, req.Subject.Organization) {
return organizationNotSystemNodesErr
}
Expand All @@ -118,8 +136,14 @@ func ValidateKubeletClientCSR(req *x509.CertificateRequest, usages sets.String)
return commonNameNotSystemNode
}

if !kubeletClientRequiredUsages.Equal(usages) {
return fmt.Errorf("usages did not match %v", kubeletClientRequiredUsages.List())
if allowOmittingUsageKeyEncipherment {
if !kubeletClientRequiredUsages.Equal(usages) && !kubeletClientRequiredUsagesNoRSA.Equal(usages) {
return fmt.Errorf("usages did not match %v", kubeletClientRequiredUsages.List())
}
} else {
if !kubeletClientRequiredUsages.Equal(usages) {
return fmt.Errorf("usages did not match %v", kubeletClientRequiredUsages.List())
}
}

return nil
Expand Down
20 changes: 10 additions & 10 deletions pkg/apis/certificates/v1beta1/defaults.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -56,27 +56,27 @@ func DefaultSignerNameFromSpec(obj *certificatesv1beta1.CertificateSigningReques
// Set the signerName to 'legacy-unknown' as the CSR could not be
// recognised.
return certificatesv1beta1.LegacyUnknownSignerName
case IsKubeletClientCSR(csr, obj.Usages):
case IsKubeletClientCSR(csr, obj.Usages, false):
return certificatesv1beta1.KubeAPIServerClientKubeletSignerName
case IsKubeletServingCSR(csr, obj.Usages):
case IsKubeletServingCSR(csr, obj.Usages, false):
return certificatesv1beta1.KubeletServingSignerName
default:
return certificatesv1beta1.LegacyUnknownSignerName
}
}

func IsKubeletServingCSR(req *x509.CertificateRequest, usages []certificatesv1beta1.KeyUsage) bool {
return certificates.IsKubeletServingCSR(req, usagesToSet(usages))
func IsKubeletServingCSR(req *x509.CertificateRequest, usages []certificatesv1beta1.KeyUsage, allowOmittingUsageKeyEncipherment bool) bool {
return certificates.IsKubeletServingCSR(req, usagesToSet(usages), allowOmittingUsageKeyEncipherment)
}
func ValidateKubeletServingCSR(req *x509.CertificateRequest, usages []certificatesv1beta1.KeyUsage) error {
return certificates.ValidateKubeletServingCSR(req, usagesToSet(usages))
func ValidateKubeletServingCSR(req *x509.CertificateRequest, usages []certificatesv1beta1.KeyUsage, allowOmittingUsageKeyEncipherment bool) error {
return certificates.ValidateKubeletServingCSR(req, usagesToSet(usages), allowOmittingUsageKeyEncipherment)
}

func IsKubeletClientCSR(req *x509.CertificateRequest, usages []certificatesv1beta1.KeyUsage) bool {
return certificates.IsKubeletClientCSR(req, usagesToSet(usages))
func IsKubeletClientCSR(req *x509.CertificateRequest, usages []certificatesv1beta1.KeyUsage, allowOmittingUsageKeyEncipherment bool) bool {
return certificates.IsKubeletClientCSR(req, usagesToSet(usages), allowOmittingUsageKeyEncipherment)
}
func ValidateKubeletClientCSR(req *x509.CertificateRequest, usages []certificatesv1beta1.KeyUsage) error {
return certificates.ValidateKubeletClientCSR(req, usagesToSet(usages))
func ValidateKubeletClientCSR(req *x509.CertificateRequest, usages []certificatesv1beta1.KeyUsage, allowOmittingUsageKeyEncipherment bool) error {
return certificates.ValidateKubeletClientCSR(req, usagesToSet(usages), allowOmittingUsageKeyEncipherment)
}

func usagesToSet(usages []certificatesv1beta1.KeyUsage) sets.String {
Expand Down
67 changes: 59 additions & 8 deletions pkg/apis/certificates/v1beta1/defaults_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -40,15 +40,28 @@ func TestIsKubeletServingCSR(t *testing.T) {
return csr
}
tests := map[string]struct {
req *x509.CertificateRequest
usages []capi.KeyUsage
exp bool
req *x509.CertificateRequest
usages []capi.KeyUsage
allowOmittingUsageKeyEncipherment bool
exp bool
}{
"defaults for kubelet-serving": {
req: newCSR(kubeletServerPEMOptions),
usages: kubeletServerUsages,
exp: true,
},
"defaults without key encipherment for kubelet-serving if allow omitting key encipherment": {
req: newCSR(kubeletServerPEMOptions),
usages: kubeletServerUsagesNoRSA,
allowOmittingUsageKeyEncipherment: true,
exp: true,
},
"defaults for kubelet-serving if allow omitting key encipherment": {
req: newCSR(kubeletServerPEMOptions),
usages: kubeletServerUsages,
allowOmittingUsageKeyEncipherment: true,
exp: true,
},
"does not default to kube-apiserver-client-kubelet if org is not 'system:nodes'": {
req: newCSR(kubeletServerPEMOptions, pemOptions{org: "not-system:nodes"}),
usages: kubeletServerUsages,
Expand All @@ -69,6 +82,17 @@ func TestIsKubeletServingCSR(t *testing.T) {
usages: kubeletServerUsages[1:],
exp: false,
},
"does not default to kubelet-serving if it is missing an expected usage if allow omitting key encipherment": {
req: newCSR(kubeletServerPEMOptions),
usages: kubeletServerUsagesNoRSA[1:],
allowOmittingUsageKeyEncipherment: true,
exp: false,
},
"does not default to kubelet-serving if it is missing an expected usage withou key encipherment": {
req: newCSR(kubeletServerPEMOptions),
usages: kubeletServerUsagesNoRSA,
exp: false,
},
"does not default to kubelet-serving if it does not specify any dnsNames or ipAddresses": {
req: newCSR(kubeletServerPEMOptions, pemOptions{ipAddresses: []net.IP{}, dnsNames: []string{}}),
usages: kubeletServerUsages[1:],
Expand All @@ -87,7 +111,7 @@ func TestIsKubeletServingCSR(t *testing.T) {
}
for name, test := range tests {
t.Run(name, func(t *testing.T) {
got := IsKubeletServingCSR(test.req, test.usages)
got := IsKubeletServingCSR(test.req, test.usages, test.allowOmittingUsageKeyEncipherment)
if test.exp != got {
t.Errorf("unexpected IsKubeletClientCSR output: exp=%v, got=%v", test.exp, got)
}
Expand All @@ -105,9 +129,10 @@ func TestIsKubeletClientCSR(t *testing.T) {
return csr
}
tests := map[string]struct {
req *x509.CertificateRequest
usages []capi.KeyUsage
exp bool
req *x509.CertificateRequest
usages []capi.KeyUsage
allowOmittingUsageKeyEncipherment bool
exp bool
}{
"defaults for kube-apiserver-client-kubelet": {
req: newCSR(kubeletClientPEMOptions),
Expand Down Expand Up @@ -154,10 +179,28 @@ func TestIsKubeletClientCSR(t *testing.T) {
usages: kubeletClientUsages[1:],
exp: false,
},
"does not default to kube-apiserver-client-kubelet if it is missing an expected usage without key encipherment": {
req: newCSR(kubeletClientPEMOptions),
usages: kubeletClientUsagesNoRSA[1:],
allowOmittingUsageKeyEncipherment: true,
exp: false,
},
"default to kube-apiserver-client-kubelet with key encipherment": {
req: newCSR(kubeletClientPEMOptions),
usages: kubeletClientUsages,
allowOmittingUsageKeyEncipherment: true,
exp: true,
},
"default to kube-apiserver-client-kubelet without key encipherment": {
req: newCSR(kubeletClientPEMOptions),
usages: kubeletClientUsagesNoRSA,
allowOmittingUsageKeyEncipherment: true,
exp: true,
},
}
for name, test := range tests {
t.Run(name, func(t *testing.T) {
got := IsKubeletClientCSR(test.req, test.usages)
got := IsKubeletClientCSR(test.req, test.usages, test.allowOmittingUsageKeyEncipherment)
if test.exp != got {
t.Errorf("unexpected IsKubeletClientCSR output: exp=%v, got=%v", test.exp, got)
}
Expand All @@ -171,6 +214,10 @@ var (
capi.UsageKeyEncipherment,
capi.UsageClientAuth,
}
kubeletClientUsagesNoRSA = []capi.KeyUsage{
capi.UsageDigitalSignature,
capi.UsageClientAuth,
}
kubeletClientPEMOptions = pemOptions{
cn: "system:node:nodename",
org: "system:nodes",
Expand All @@ -181,6 +228,10 @@ var (
capi.UsageKeyEncipherment,
capi.UsageServerAuth,
}
kubeletServerUsagesNoRSA = []capi.KeyUsage{
capi.UsageDigitalSignature,
capi.UsageServerAuth,
}
kubeletServerPEMOptions = pemOptions{
cn: "system:node:requester-name",
org: "system:nodes",
Expand Down
2 changes: 1 addition & 1 deletion pkg/controller/certificates/approver/sarapprove.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -152,7 +152,7 @@ func isNodeClientCert(csr *capi.CertificateSigningRequest, x509cr *x509.Certific
if csr.Spec.SignerName != capi.KubeAPIServerClientKubeletSignerName {
return false
}
return capihelper.IsKubeletClientCSR(x509cr, usagesToSet(csr.Spec.Usages))
return capihelper.IsKubeletClientCSR(x509cr, usagesToSet(csr.Spec.Usages), true)
}

func isSelfNodeClientCert(csr *capi.CertificateSigningRequest, x509cr *x509.CertificateRequest) bool {
Expand Down
22 changes: 22 additions & 0 deletions pkg/controller/certificates/approver/sarapprove_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -211,6 +211,28 @@ func testRecognizer(t *testing.T, cases []func(b *csrBuilder), recognizeFunc fun
t.Errorf("expected recognized to be %v", shouldRecognize)
}
})
// reset the builder to run testcase without usage key encipherment
d := csrBuilder{
signerName: capi.KubeAPIServerClientKubeletSignerName,
cn: "system:node:foo",
orgs: []string{"system:nodes"},
requestor: "system:node:foo",
usages: []capi.KeyUsage{
capi.UsageDigitalSignature,
capi.UsageClientAuth,
},
}
c(&d)
t.Run(fmt.Sprintf("csr:%#v", d), func(t *testing.T) {
csr := makeFancyTestCsr(d)
x509cr, err := k8s_certificates_v1.ParseCSR(csr.Spec.Request)
if err != nil {
t.Errorf("unexpected err: %v", err)
}
if recognizeFunc(csr, x509cr) != shouldRecognize {
t.Errorf("expected recognized to be %v", shouldRecognize)
}
})
}
}

Expand Down
4 changes: 2 additions & 2 deletions pkg/controller/certificates/signer/signer.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -248,14 +248,14 @@ func isKubeletServing(req *x509.CertificateRequest, usages []capi.KeyUsage, sign
if signerName != capi.KubeletServingSignerName {
return false, nil
}
return true, capihelper.ValidateKubeletServingCSR(req, usagesToSet(usages))
return true, capihelper.ValidateKubeletServingCSR(req, usagesToSet(usages), true)
}

func isKubeletClient(req *x509.CertificateRequest, usages []capi.KeyUsage, signerName string) (bool, error) {
if signerName != capi.KubeAPIServerClientKubeletSignerName {
return false, nil
}
return true, capihelper.ValidateKubeletClientCSR(req, usagesToSet(usages))
return true, capihelper.ValidateKubeletClientCSR(req, usagesToSet(usages), true)
}

func isKubeAPIServerClient(req *x509.CertificateRequest, usages []capi.KeyUsage, signerName string) (bool, error) {
Expand Down
55 changes: 55 additions & 0 deletions pkg/controller/certificates/signer/signer_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -143,6 +143,24 @@ func TestHandle(t *testing.T) {
}
},
},
{
name: "should sign without key encipherment if signerName is kubernetes.io/kube-apiserver-client",
signerName: "kubernetes.io/kube-apiserver-client",
commonName: "hello-world",
org: []string{"some-org"},
usages: []capi.KeyUsage{capi.UsageClientAuth, capi.UsageDigitalSignature},
approved: true,
verify: func(t *testing.T, as []testclient.Action) {
if len(as) != 1 {
t.Errorf("expected one Update action but got %d", len(as))
return
}
csr := as[0].(testclient.UpdateAction).GetObject().(*capi.CertificateSigningRequest)
if len(csr.Status.Certificate) == 0 {
t.Errorf("expected certificate to be issued but it was not")
}
},
},
{
name: "should refuse to sign if signerName is kubernetes.io/kube-apiserver-client and contains an unexpected usage",
signerName: "kubernetes.io/kube-apiserver-client",
Expand Down Expand Up @@ -182,6 +200,24 @@ func TestHandle(t *testing.T) {
}
},
},
{
name: "should sign without usage key encipherment if signerName is kubernetes.io/kube-apiserver-client-kubelet",
signerName: "kubernetes.io/kube-apiserver-client-kubelet",
commonName: "system:node:hello-world",
org: []string{"system:nodes"},
usages: []capi.KeyUsage{capi.UsageClientAuth, capi.UsageDigitalSignature},
approved: true,
verify: func(t *testing.T, as []testclient.Action) {
if len(as) != 1 {
t.Errorf("expected one Update action but got %d", len(as))
return
}
csr := as[0].(testclient.UpdateAction).GetObject().(*capi.CertificateSigningRequest)
if len(csr.Status.Certificate) == 0 {
t.Errorf("expected certificate to be issued but it was not")
}
},
},
{
name: "should sign if signerName is kubernetes.io/legacy-unknown",
signerName: "kubernetes.io/legacy-unknown",
Expand Down Expand Up @@ -216,6 +252,25 @@ func TestHandle(t *testing.T) {
}
},
},
{
name: "should sign without usage key encipherment if signerName is kubernetes.io/kubelet-serving",
signerName: "kubernetes.io/kubelet-serving",
commonName: "system:node:testnode",
org: []string{"system:nodes"},
usages: []capi.KeyUsage{capi.UsageServerAuth, capi.UsageDigitalSignature},
dnsNames: []string{"example.com"},
approved: true,
verify: func(t *testing.T, as []testclient.Action) {
if len(as) != 1 {
t.Errorf("expected one Update action but got %d", len(as))
return
}
csr := as[0].(testclient.UpdateAction).GetObject().(*capi.CertificateSigningRequest)
if len(csr.Status.Certificate) == 0 {
t.Errorf("expected certificate to be issued but it was not")
}
},
},
{
name: "should do nothing if failed",
signerName: "kubernetes.io/kubelet-serving",
Expand Down

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