Add support to CRL (#3164)

Signed-off-by: Ricardo Pchevuzinske Katz <ricardo.katz@serpro.gov.br>

Add support to CRL

Signed-off-by: Ricardo Pchevuzinske Katz <ricardo.katz@serpro.gov.br>

docs/examples/auth/client-certs/README.md

@@ -44,6 +44,12 @@ Authentication to work properly.
     kubectl create secret generic ca-secret --from-file=tls.crt=server.crt --from-file=tls.key=server.key --from-file=ca.crt=ca.crt
     ```
 
+3. If you want to also enable Certificate Revocation List verification you can 
+   create the secret also containing the CRL file in PEM format:
+   ```bash
+   kubectl create secret generic ca-secret --from-file=ca.crt=ca.crt --from-file=ca.crl=ca.crl
+   ```
+
 Note: The CA Certificate must contain the trusted certificate authority chain to verify client certificates.
 
 ## Setup Instructions

internal/ingress/controller/store/backend_ssl.go

@@ -84,6 +84,8 @@ func (s *k8sStore) getPemCertificate(secretName string) (*ingress.SSLCert, error
 	key, okkey := secret.Data[apiv1.TLSPrivateKeyKey]
 	ca := secret.Data["ca.crt"]
 
+	crl := secret.Data["ca.crl"]
+
 	auth := secret.Data["auth"]
 
 	// namespace/secretName -> namespace-secretName
@@ -117,12 +119,25 @@ func (s *k8sStore) getPemCertificate(secretName string) (*ingress.SSLCert, error
 			if err != nil {
 				return nil, fmt.Errorf("error configuring CA certificate: %v", err)
 			}
+
+			if len(crl) > 0 {
+				err = ssl.ConfigureCRL(nsSecName, crl, sslCert)
+				if err != nil {
+					return nil, fmt.Errorf("error configuring CRL certificate: %v", err)
+				}
+
+			}
 		}
 
 		msg := fmt.Sprintf("Configuring Secret %q for TLS encryption (CN: %v)", secretName, sslCert.CN)
 		if ca != nil {
 			msg += " and authentication"
 		}
+
+		if crl != nil {
+			msg += " and CRL"
+		}
+
 		klog.V(3).Info(msg)
 	} else if len(ca) > 0 {
 		sslCert, err = ssl.CreateCACert(ca)
@@ -135,6 +150,12 @@ func (s *k8sStore) getPemCertificate(secretName string) (*ingress.SSLCert, error
 			return nil, fmt.Errorf("error configuring CA certificate: %v", err)
 		}
 
+		if len(crl) > 0 {
+			err = ssl.ConfigureCRL(nsSecName, crl, sslCert)
+			if err != nil {
+				return nil, err
+			}
+		}
 		// makes this secret in 'syncSecret' to be used for Certificate Authentication
 		// this does not enable Certificate Authentication
 		klog.V(3).Infof("Configuring Secret %q for TLS authentication", secretName)

internal/ingress/controller/store/store.go

@@ -819,6 +819,8 @@ func (s *k8sStore) GetAuthCertificate(name string) (*resolver.AuthSSLCert, error
 		Secret:      name,
 		CAFileName:  cert.CAFileName,
 		CASHA:       cert.CASHA,
+		CRLFileName: cert.CRLFileName,
+		CRLSHA:      cert.CRLSHA,
 	}, nil
 }
 

internal/ingress/resolver/main.go

@@ -32,12 +32,11 @@ type Resolver interface {
 	// GetSecret searches for secrets containing the namespace and name using a the character /
 	GetSecret(string) (*apiv1.Secret, error)
 
-	// GetAuthCertificate resolves a given secret name into an SSL certificate.
-	// The secret must contain 3 keys named:
+	// GetAuthCertificate resolves a given secret name into an SSL certificate and CRL.
+	// The secret must contain 2 keys named:
 
 	//   ca.crt: contains the certificate chain used for authentication
-	//   tls.crt: contains the server certificate
-	//   tls.key: contains the server key
+	//   ca.crl: contains the revocation list used for authentication
 	GetAuthCertificate(string) (*AuthSSLCert, error)
 
 	// GetService searches for services containing the namespace and name using a the character /
@@ -53,6 +52,10 @@ type AuthSSLCert struct {
 	CAFileName string `json:"caFilename"`
 	// CASHA contains the SHA1 hash of the 'ca.crt' or combinations of (tls.crt, tls.key, tls.crt) depending on certs in secret
 	CASHA string `json:"caSha"`
+	// CRLFileName contains the path to the secrets 'ca.crl'
+	CRLFileName string `json:"crlFileName"`
+	// CRLSHA contains the SHA1 hash of the 'ca.crl' file
+	CRLSHA string `json:"crlSha"`
 }
 
 // Equal tests for equality between two AuthSSLCert types
@@ -74,5 +77,12 @@ func (asslc1 *AuthSSLCert) Equal(assl2 *AuthSSLCert) bool {
 		return false
 	}
 
+	if asslc1.CRLFileName != assl2.CRLFileName {
+		return false
+	}
+	if asslc1.CRLSHA != assl2.CRLSHA {
+		return false
+	}
+
 	return true
 }

internal/ingress/sslcert.go

@@ -37,6 +37,11 @@ type SSLCert struct {
 	// This is used to detect changes in the secret that contains certificates
 	CASHA string `json:"caSha"`
 
+	// CRLFileName contains the path to the file with the Certificate Revocation List
+	CRLFileName string `json:"crlFileName"`
+	// CRLSHA contains the sha1 of the pem file.
+	CRLSHA string `json:"crlSha"`
+
 	// PemFileName contains the path to the file with the certificate and key concatenated
 	PemFileName string `json:"pemFileName"`
 

internal/net/ssl/ssl.go

@@ -211,6 +211,38 @@ func ConfigureCACertWithCertAndKey(name string, ca []byte, sslCert *ingress.SSLC
 	return ioutil.WriteFile(sslCert.CAFileName, buffer.Bytes(), 0644)
 }
 
+// ConfigureCRL creates a CRL file and append it into the SSLCert
+func ConfigureCRL(name string, crl []byte, sslCert *ingress.SSLCert) error {
+
+	crlName := fmt.Sprintf("crl-%v.pem", name)
+	crlFileName := fmt.Sprintf("%v/%v", file.DefaultSSLDirectory, crlName)
+
+	pemCRLBlock, _ := pem.Decode(crl)
+	if pemCRLBlock == nil {
+		return fmt.Errorf("no valid PEM formatted block found in CRL %v", name)
+	}
+	// If the first certificate does not start with 'X509 CRL' it's invalid and must not be used.
+	if pemCRLBlock.Type != "X509 CRL" {
+		return fmt.Errorf("CRL file %v contains invalid data, and must be created only with PEM formatted certificates", name)
+	}
+
+	_, err := x509.ParseCRL(pemCRLBlock.Bytes)
+	if err != nil {
+		return fmt.Errorf(err.Error())
+	}
+
+	err = ioutil.WriteFile(crlFileName, crl, 0644)
+	if err != nil {
+		return fmt.Errorf("could not write CRL file %v: %v", crlFileName, err)
+	}
+
+	sslCert.CRLFileName = crlFileName
+	sslCert.CRLSHA = file.SHA1(crlFileName)
+
+	return nil
+
+}
+
 // ConfigureCACert is similar to ConfigureCACertWithCertAndKey but it creates a separate file
 // for CA cert and writes only ca into it and then sets relevant fields in sslCert
 func ConfigureCACert(name string, ca []byte, sslCert *ingress.SSLCert) error {

internal/net/ssl/ssl_test.go

@@ -39,6 +39,7 @@ import (
 	"time"
 
 	certutil "k8s.io/client-go/util/cert"
+	"k8s.io/ingress-nginx/internal/file"
 )
 
 // generateRSACerts generates a self signed certificate using a self generated ca
@@ -183,11 +184,60 @@ func TestConfigureCACert(t *testing.T) {
 	if err != nil {
 		t.Fatalf("unexpected error creating SSL certificate: %v", err)
 	}
-	if sslCert.CAFileName == "" {
+
+	caFilename := fmt.Sprintf("%v/ca-%v.pem", file.DefaultSSLDirectory, cn)
+
+	if sslCert.CAFileName != caFilename {
 		t.Fatalf("expected a valid CA file name")
 	}
 }
 
+func TestConfigureCRL(t *testing.T) {
+	// Demo CRL from https://csrc.nist.gov/projects/pki-testing/sample-certificates-and-crls
+	// Converted to PEM to be tested
+	// SHA: ef21f9c97ec2ef84ba3b2ab007c858a6f760d813
+	var crl = []byte(`-----BEGIN X509 CRL-----
+MIIBYDCBygIBATANBgkqhkiG9w0BAQUFADBDMRMwEQYKCZImiZPyLGQBGRYDY29t
+MRcwFQYKCZImiZPyLGQBGRYHZXhhbXBsZTETMBEGA1UEAxMKRXhhbXBsZSBDQRcN
+MDUwMjA1MTIwMDAwWhcNMDUwMjA2MTIwMDAwWjAiMCACARIXDTA0MTExOTE1NTcw
+M1owDDAKBgNVHRUEAwoBAaAvMC0wHwYDVR0jBBgwFoAUCGivhTPIOUp6+IKTjnBq
+SiCELDIwCgYDVR0UBAMCAQwwDQYJKoZIhvcNAQEFBQADgYEAItwYffcIzsx10NBq
+m60Q9HYjtIFutW2+DvsVFGzIF20f7pAXom9g5L2qjFXejoRvkvifEBInr0rUL4Xi
+NkR9qqNMJTgV/wD9Pn7uPSYS69jnK2LiK8NGgO94gtEVxtCccmrLznrtZ5mLbnCB
+fUNCdMGmr8FVF6IzTNYGmCuk/C4=
+-----END X509 CRL-----`)
+
+	cn := "demo-crl"
+	_, ca, err := generateRSACerts(cn)
+	if err != nil {
+		t.Fatalf("unexpected error creating SSL certificate: %v", err)
+	}
+	c := encodeCertPEM(ca.Cert)
+
+	sslCert, err := CreateCACert(c)
+	if err != nil {
+		t.Fatalf("unexpected error creating SSL certificate: %v", err)
+	}
+	if sslCert.CRLFileName != "" {
+		t.Fatalf("expected CRLFileName to be empty")
+	}
+	if sslCert.Certificate == nil {
+		t.Fatalf("expected Certificate to be set")
+	}
+
+	err = ConfigureCRL(cn, crl, sslCert)
+	if err != nil {
+		t.Fatalf("unexpected error creating CRL file: %v", err)
+	}
+
+	crlFilename := fmt.Sprintf("%v/crl-%v.pem", file.DefaultSSLDirectory, cn)
+	if sslCert.CRLFileName != crlFilename {
+		t.Fatalf("expected a valid CRL file name")
+	}
+	if sslCert.CRLSHA != "ef21f9c97ec2ef84ba3b2ab007c858a6f760d813" {
+		t.Fatalf("the expected CRL SHA wasn't found")
+	}
+}
 func TestCreateSSLCert(t *testing.T) {
 	cert, _, err := generateRSACerts("echoheaders")
 	if err != nil {

rootfs/etc/nginx/template/nginx.tmpl

@@ -811,6 +811,12 @@ stream {
         ssl_client_certificate                  {{ $server.CertificateAuth.CAFileName }};
         ssl_verify_client                       {{ $server.CertificateAuth.VerifyClient }};
         ssl_verify_depth                        {{ $server.CertificateAuth.ValidationDepth }};
+
+        {{ if not (empty $server.CertificateAuth.CRLFileName) }}
+        # PEM sha: {{ $server.CertificateAuth.CRLSHA }}
+        ssl_crl                  {{ $server.CertificateAuth.CRLFileName }};
+        {{ end }}
+
         {{ if not (empty $server.CertificateAuth.ErrorPage)}}
         error_page 495 496 = {{ $server.CertificateAuth.ErrorPage }};
         {{ end }}