Implement upstream tls backend verification with ca cert and optional

subject alt name

Signed-off-by: Steve Sloka <slokas@vmware.com>

apis/contour/v1beta1/ingressroute.go

@@ -96,6 +96,8 @@ type Service struct {
 	HealthCheck *HealthCheck `json:"healthCheck,omitempty"`
 	// LB Algorithm to apply (see https://github.com/heptio/contour/blob/master/design/ingressroute-design.md#load-balancing)
 	Strategy string `json:"strategy,omitempty"`
+	// UpstreamValidation defines how to verify the backend service's certificate
+	UpstreamValidation *UpstreamValidation `json:"validation,omitempty"`
 }
 
 // Delegate allows for delegating VHosts to other IngressRoutes
@@ -141,6 +143,14 @@ type RetryPolicy struct {
 	PerTryTimeout string `json:"perTryTimeout,omitempty"`
 }
 
+// UpstreamValidation defines how to verify the backend service's certificate
+type UpstreamValidation struct {
+	// Name of the Kubernetes secret be used to validate the certificate presented by the backend
+	CASecret string `json:"caSecret"`
+	// Ket which is expected to be present in the 'subjectAltName' of the presented certificate
+	SubjectName string `json:"subjectname,omitempty""`
+}
+
 // Status reports the current state of the IngressRoute
 type Status struct {
 	CurrentStatus string `json:"currentStatus"`

docs/ingressroute.md

@@ -273,6 +273,37 @@ spec:
           permitInsecure: true
 ```
 
+#### Upstream TLS
+
+An IngressRoute route can proxy to an upstream TLS connection by first annotating the upstream Kubernetes service with: `contour.heptio.com/upstream-protocol.tls: "443,https"`.
+This annoation tells Contour which port should be used for the TLS connection.
+In this example, the upstream service is named `https` and uses port `443`.
+Additionally, it is possible for Envoy to verify the backend service's certificate.
+The service of an `IngressRoute` can optionally specify a `validation` struct which has a manditory `caSecret` key as well as an optional `subjectname`.
+
+Note: If spec.routes.services[].validation is present, spec.routes.services[].{name,port} must point to a service with a matching contour.heptio.com/upstream-protocol.tls Service annotation. 
+If the Service annotation is not present or incorrect, the route is rejected with an appropriate status message.
+
+##### Sample YAML
+
+```yaml
+apiVersion: contour.heptio.com/v1beta1
+kind: IngressRoute
+metadata:
+  name: secure-backend
+spec:
+  virtualhost:
+    fqdn: www.example.com  
+  routes:
+    - match: /
+      services:
+        - name: service
+          port: 8443
+          validation:
+            caSecret: my-certificate-authority
+            subjectname: backend.example.com
+```
+
 #### TLS Certificate Delegation
 
 In order to support wildcard certificates, TLS certificates for a `*.somedomain.com`, which are stored in a namespace controlled by the cluster administrator, Contour supports a facility known as TLS Certificate Delegation.

internal/dag/builder.go

@@ -74,8 +74,8 @@ type builder struct {
 }
 
 // lookupHTTPService returns a HTTPService that matches the meta and port supplied.
-func (b *builder) lookupHTTPService(m meta, port intstr.IntOrString, strategy string, hc *ingressroutev1.HealthCheck) *HTTPService {
-	s := b.lookupService(m, port, strategy, hc)
+func (b *builder) lookupHTTPService(m meta, port intstr.IntOrString, strategy string, hc *ingressroutev1.HealthCheck, uv *ingressroutev1.UpstreamValidation) *HTTPService {
+	s := b.lookupService(m, port, strategy, hc, uv)
 	switch s := s.(type) {
 	case *HTTPService:
 		return s
@@ -87,10 +87,10 @@ func (b *builder) lookupHTTPService(m meta, port intstr.IntOrString, strategy st
 		for i := range svc.Spec.Ports {
 			p := &svc.Spec.Ports[i]
 			if int(p.Port) == port.IntValue() {
-				return b.addHTTPService(svc, p, strategy, hc)
+				return b.addHTTPService(svc, p, strategy, hc, uv)
 			}
 			if port.String() == p.Name {
-				return b.addHTTPService(svc, p, strategy, hc)
+				return b.addHTTPService(svc, p, strategy, hc, uv)
 			}
 		}
 		return nil
@@ -101,8 +101,8 @@ func (b *builder) lookupHTTPService(m meta, port intstr.IntOrString, strategy st
 }
 
 // lookupTCPService returns a TCPService that matches the meta and port supplied.
-func (b *builder) lookupTCPService(m meta, port intstr.IntOrString, strategy string, hc *ingressroutev1.HealthCheck) *TCPService {
-	s := b.lookupService(m, port, strategy, hc)
+func (b *builder) lookupTCPService(m meta, port intstr.IntOrString, strategy string, hc *ingressroutev1.HealthCheck, uv *ingressroutev1.UpstreamValidation) *TCPService {
+	s := b.lookupService(m, port, strategy, hc, uv)
 	switch s := s.(type) {
 	case *TCPService:
 		return s
@@ -126,17 +126,18 @@ func (b *builder) lookupTCPService(m meta, port intstr.IntOrString, strategy str
 		return nil
 	}
 }
-func (b *builder) lookupService(m meta, port intstr.IntOrString, strategy string, hc *ingressroutev1.HealthCheck) Service {
+func (b *builder) lookupService(m meta, port intstr.IntOrString, strategy string, hc *ingressroutev1.HealthCheck, uv *ingressroutev1.UpstreamValidation) Service {
 	if port.Type != intstr.Int {
 		// can't handle, give up
 		return nil
 	}
 	sm := servicemeta{
-		name:        m.name,
-		namespace:   m.namespace,
-		port:        int32(port.IntValue()),
-		strategy:    strategy,
-		healthcheck: healthcheckToString(hc),
+		name:               m.name,
+		namespace:          m.namespace,
+		port:               int32(port.IntValue()),
+		strategy:           strategy,
+		healthcheck:        healthcheckToString(hc),
+		upstreamvalidation: upstreamValidationToString(uv),
 	}
 	s, ok := b.services[sm]
 	if !ok {
@@ -149,7 +150,11 @@ func healthcheckToString(hc *ingressroutev1.HealthCheck) string {
 	return fmt.Sprintf("%#v", hc)
 }
 
-func (b *builder) addHTTPService(svc *v1.Service, port *v1.ServicePort, strategy string, hc *ingressroutev1.HealthCheck) *HTTPService {
+func upstreamValidationToString(uv *ingressroutev1.UpstreamValidation) string {
+	return fmt.Sprintf("%#v", uv)
+}
+
+func (b *builder) addHTTPService(svc *v1.Service, port *v1.ServicePort, strategy string, hc *ingressroutev1.HealthCheck, uv *ingressroutev1.UpstreamValidation) *HTTPService {
 	if b.services == nil {
 		b.services = make(map[servicemeta]Service)
 	}
@@ -171,13 +176,25 @@ func (b *builder) addHTTPService(svc *v1.Service, port *v1.ServicePort, strategy
 			MaxRequests:        parseAnnotation(svc.Annotations, annotationMaxRequests),
 			MaxRetries:         parseAnnotation(svc.Annotations, annotationMaxRetries),
 			HealthCheck:        hc,
+			UpstreamValidation: b.addUpstreamValidation(uv, svc),
 		},
 		Protocol: protocol,
 	}
 	b.services[s.toMeta()] = s
 	return s
 }
 
+func (b *builder) addUpstreamValidation(uv *ingressroutev1.UpstreamValidation, svc *v1.Service) *UpstreamValidation {
+	if uv != nil {
+		val := &UpstreamValidation{
+			Certificate: b.lookupSecret(meta{name: uv.CASecret, namespace: svc.Namespace}),
+			SubjectName: uv.SubjectName,
+		}
+		return val
+	}
+	return nil
+}
+
 func (b *builder) addTCPService(svc *v1.Service, port *v1.ServicePort, strategy string, hc *ingressroutev1.HealthCheck) *TCPService {
 	if b.services == nil {
 		b.services = make(map[servicemeta]Service)
@@ -466,7 +483,7 @@ func (b *builder) computeIngresses() {
 				r := prefixRoute(ing, prefix)
 				be := httppath.Backend
 				m := meta{name: be.ServiceName, namespace: ing.Namespace}
-				if s := b.lookupHTTPService(m, be.ServicePort, "", nil); s != nil {
+				if s := b.lookupHTTPService(m, be.ServicePort, "", nil, nil); s != nil {
 					r.addHTTPService(s, 0)
 				}
 
@@ -661,7 +678,7 @@ func (b *builder) processRoutes(ir *ingressroutev1.IngressRoute, prefixMatch str
 					return
 				}
 				m := meta{name: service.Name, namespace: ir.Namespace}
-				if s := b.lookupHTTPService(m, intstr.FromInt(service.Port), service.Strategy, service.HealthCheck); s != nil {
+				if s := b.lookupHTTPService(m, intstr.FromInt(service.Port), service.Strategy, service.HealthCheck, service.UpstreamValidation); s != nil {
 					r.addHTTPService(s, service.Weight)
 				}
 			}
@@ -722,7 +739,7 @@ func (b *builder) processTCPProxy(ir *ingressroutev1.IngressRoute, visited []*in
 		var proxy TCPProxy
 		for _, service := range tcpproxy.Services {
 			m := meta{name: service.Name, namespace: ir.Namespace}
-			s := b.lookupTCPService(m, intstr.FromInt(service.Port), service.Strategy, service.HealthCheck)
+			s := b.lookupTCPService(m, intstr.FromInt(service.Port), service.Strategy, service.HealthCheck, service.UpstreamValidation)
 			if s == nil {
 				b.setStatus(Status{Object: ir, Status: StatusInvalid, Description: fmt.Sprintf("tcpproxy: service %s/%s/%d: not found", ir.Namespace, service.Name, service.Port), Vhost: host})
 				return

internal/dag/builder_test.go

@@ -2724,6 +2724,7 @@ func TestBuilderLookupHTTPService(t *testing.T) {
 		port        intstr.IntOrString
 		strategy    string
 		healthcheck *ingressroutev1.HealthCheck
+		upstreamval *ingressroutev1.UpstreamValidation
 		want        *HTTPService
 	}{
 		"lookup service by port number": {
@@ -2757,7 +2758,7 @@ func TestBuilderLookupHTTPService(t *testing.T) {
 					},
 				},
 			}
-			got := b.lookupHTTPService(tc.meta, tc.port, tc.strategy, tc.healthcheck)
+			got := b.lookupHTTPService(tc.meta, tc.port, tc.strategy, tc.healthcheck, tc.upstreamval)
 			if diff := cmp.Diff(tc.want, got); diff != "" {
 				t.Fatal(diff)
 			}

internal/dag/dag.go

@@ -20,7 +20,7 @@ import (
 
 	"github.com/envoyproxy/go-control-plane/envoy/api/v2/auth"
 	ingressroutev1 "github.com/heptio/contour/apis/contour/v1beta1"
-	"k8s.io/api/core/v1"
+	v1 "k8s.io/api/core/v1"
 )
 
 // A DAG represents a directed acylic graph of objects representing the relationship
@@ -93,6 +93,17 @@ type RetryPolicy struct {
 	PerTryTimeout time.Duration
 }
 
+// UpstreamValidation defines how to validate the certificate on the upstream service
+type UpstreamValidation struct {
+	// Certificate holds a reference to the Secret containing the CA to be used to
+	// verify the upstream connection.
+	Certificate *Secret
+
+	// SubjectName holds an optional subject name which Envoy will check against the
+	// certificate presented by the upstream.
+	SubjectName string
+}
+
 func (r *Route) addHTTPService(s *HTTPService, weight int) {
 	r.Clusters = append(r.Clusters, &Cluster{
 		Upstream: s,
@@ -228,14 +239,18 @@ type TCPService struct {
 	MaxRetries int
 
 	HealthCheck *ingressroutev1.HealthCheck
+
+	// UpstreamValidation defines how to verify the backend service's certificate
+	UpstreamValidation *UpstreamValidation
 }
 
 type servicemeta struct {
-	name        string
-	namespace   string
-	port        int32
-	strategy    string
-	healthcheck string // %#v of *ingressroutev1.HealthCheck
+	name               string
+	namespace          string
+	port               int32
+	strategy           string
+	healthcheck        string // %#v of *ingressroutev1.HealthCheck
+	upstreamvalidation string // %#v of *ingressroutev1.UpstreamValidation
 }
 
 func (s *TCPService) toMeta() servicemeta {