allow specifying custom dh param

controllers/nginx/configuration.md

@@ -336,7 +336,7 @@ The recommendation above prioritizes algorithms that provide perfect [forward se
 Please check the [Mozilla SSL Configuration Generator](https://mozilla.github.io/server-side-tls/ssl-config-generator/).
 
 
-**ssl-dh-param:** sets the Base64 string that contains Diffie-Hellman key to help with "Perfect Forward Secrecy".
+**ssl-dh-param:** Sets the name of the secret that contains Diffie-Hellman key to help with "Perfect Forward Secrecy".
 https://www.openssl.org/docs/manmaster/apps/dhparam.html
 https://wiki.mozilla.org/Security/Server_Side_TLS#DHE_handshake_and_dhparam
 http://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_dhparam

controllers/nginx/pkg/cmd/controller/nginx.go

@@ -25,6 +25,7 @@ import (
 	"net/http"
 	"os"
 	"os/exec"
+	"strings"
 	"syscall"
 	"time"
 
@@ -38,6 +39,7 @@ import (
 	"k8s.io/ingress/controllers/nginx/pkg/version"
 	"k8s.io/ingress/core/pkg/ingress"
 	"k8s.io/ingress/core/pkg/ingress/defaults"
+	"k8s.io/ingress/core/pkg/net/ssl"
 )
 
 const (
@@ -346,6 +348,32 @@ func (n *NGINXController) OnUpdate(ingressCfg ingress.Configuration) ([]byte, er
 		}
 	}
 
+	sslDHParam := ""
+	if cfg.SSLDHParam != "" {
+		secretName := cfg.SSLDHParam
+		s, exists, err := n.storeLister.Secret.GetByKey(secretName)
+		if err != nil {
+			glog.Warningf("unexpected error reading secret %v: %v", secretName, err)
+		}
+
+		if exists {
+			secret := s.(*api.Secret)
+			nsSecName := strings.Replace(secretName, "/", "-", -1)
+
+			dh, ok := secret.Data["dhparam.pem"]
+			if ok {
+				pemFileName, err := ssl.AddOrUpdateDHParam(nsSecName, dh)
+				if err != nil {
+					glog.Warningf("unexpected error adding or updating dhparam %v file: %v", nsSecName, err)
+				} else {
+					sslDHParam = pemFileName
+				}
+			}
+		}
+	}
+
+	cfg.SSLDHParam = sslDHParam
+
 	content, err := n.t.Write(config.TemplateConfig{
 		ProxySetHeaders:     setHeaders,
 		MaxOpenFiles:        maxOpenFiles,

controllers/nginx/pkg/config/config.go

@@ -191,7 +191,7 @@ type Configuration struct {
 	// http://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_ciphers
 	SSLCiphers string `json:"ssl-ciphers,omitempty"`
 
-	// Base64 string that contains Diffie-Hellman key to help with "Perfect Forward Secrecy"
+	// The secret that contains Diffie-Hellman key to help with "Perfect Forward Secrecy"
 	// https://www.openssl.org/docs/manmaster/apps/dhparam.html
 	// https://wiki.mozilla.org/Security/Server_Side_TLS#DHE_handshake_and_dhparam
 	// http://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_dhparam

core/pkg/net/ssl/ssl.go

@@ -175,25 +175,52 @@ func AddCertAuth(name string, ca []byte) (*ingress.SSLCert, error) {
 	}, nil
 }
 
-// SearchDHParamFile iterates all the secrets mounted inside the /etc/nginx-ssl directory
-// in order to find a file with the name dhparam.pem. If such file exists it will
-// returns the path. If not it just returns an empty string
-func SearchDHParamFile(baseDir string) string {
-	files, _ := ioutil.ReadDir(baseDir)
-	for _, file := range files {
-		if !file.IsDir() {
-			continue
-		}
+// AddOrUpdateDHParam creates a dh parameters file with the specified name
+func AddOrUpdateDHParam(name string, dh []byte) (string, error) {
+	pemName := fmt.Sprintf("%v.pem", name)
+	pemFileName := fmt.Sprintf("%v/%v", ingress.DefaultSSLDirectory, pemName)
 
-		dhPath := fmt.Sprintf("%v/%v/dhparam.pem", baseDir, file.Name())
-		if _, err := os.Stat(dhPath); err == nil {
-			glog.Infof("using file '%v' for parameter ssl_dhparam", dhPath)
-			return dhPath
-		}
+	tempPemFile, err := ioutil.TempFile(ingress.DefaultSSLDirectory, pemName)
+
+	glog.V(3).Infof("Creating temp file %v for DH param: %v", tempPemFile.Name(), pemName)
+	if err != nil {
+		return "", fmt.Errorf("could not create temp pem file %v: %v", pemFileName, err)
+	}
+
+	_, err = tempPemFile.Write(dh)
+	if err != nil {
+		return "", fmt.Errorf("could not write to pem file %v: %v", tempPemFile.Name(), err)
+	}
+
+	err = tempPemFile.Close()
+	if err != nil {
+		return "", fmt.Errorf("could not close temp pem file %v: %v", tempPemFile.Name(), err)
+	}
+
+	pemCerts, err := ioutil.ReadFile(tempPemFile.Name())
+	if err != nil {
+		_ = os.Remove(tempPemFile.Name())
+		return "", err
+	}
+
+	pemBlock, _ := pem.Decode(pemCerts)
+	if pemBlock == nil {
+		_ = os.Remove(tempPemFile.Name())
+		return "", fmt.Errorf("No valid PEM formatted block found")
+	}
+
+	// If the file does not start with 'BEGIN DH PARAMETERS' it's invalid and must not be used.
+	if pemBlock.Type != "DH PARAMETERS" {
+		_ = os.Remove(tempPemFile.Name())
+		return "", fmt.Errorf("Certificate %v contains invalid data", name)
+	}
+
+	err = os.Rename(tempPemFile.Name(), pemFileName)
+	if err != nil {
+		return "", fmt.Errorf("could not move temp pem file %v to destination %v: %v", tempPemFile.Name(), pemFileName, err)
 	}
 
-	glog.Warning("no file dhparam.pem found in secrets")
-	return ""
+	return pemFileName, nil
 }
 
 // PemSHA1 returns the SHA1 of a pem file. This is used to

examples/customization/ssl-dh-param/nginx/README.md

@@ -0,0 +1,79 @@
+# Deploying the Nginx Ingress controller
+
+This example aims to demonstrate the deployment of an nginx ingress controller and
+use a ConfigMap to configure custom Diffie-Hellman parameters file to help with
+"Perfect Forward Secrecy".
+
+## Default Backend
+
+The default backend is a Service capable of handling all url paths and hosts the
+nginx controller doesn't understand. This most basic implementation just returns
+a 404 page:
+
+```console
+$ kubectl apply -f default-backend.yaml
+deployment "default-http-backend" created
+service "default-http-backend" created
+
+$ kubectl -n kube-system get po
+NAME                                    READY     STATUS    RESTARTS   AGE
+default-http-backend-2657704409-qgwdd   1/1       Running   0          28s
+```
+
+## Custom configuration
+
+```console
+$ cat nginx-load-balancer-conf.yaml
+apiVersion: v1
+data:
+  ssl-dh-param: "kube-system/lb-dhparam"
+kind: ConfigMap
+metadata:
+  name: nginx-load-balancer-conf
+```
+
+```console
+$ kubectl create -f nginx-load-balancer-conf.yaml
+```
+
+## Custom DH parameters secret
+
+```console
+$> openssl dhparam 1024 2> /dev/null | base64
+LS0tLS1CRUdJTiBESCBQQVJBTUVURVJ...
+```
+
+```console
+$ cat ssl-dh-param.yaml
+apiVersion: v1
+data:
+  dhparam.pem: "LS0tLS1CRUdJTiBESCBQQVJBTUVURVJ..."
+kind: Secret
+type: Opaque
+metadata:
+  name: lb-dhparam
+  namespace: kube-system
+```
+
+```console
+$ kubectl create -f ssl-dh-param.yaml
+```
+
+## Controller
+
+You can deploy the controller as follows:
+
+```console
+$ kubectl apply -f nginx-ingress-controller.yaml
+deployment "nginx-ingress-controller" created
+
+$ kubectl -n kube-system get po
+NAME                                       READY     STATUS    RESTARTS   AGE
+default-http-backend-2657704409-qgwdd      1/1       Running   0          2m
+nginx-ingress-controller-873061567-4n3k2   1/1       Running   0          42s
+```
+
+## Test
+
+Check the contents of the configmap is present in the nginx.conf file using:
+`kubectl exec nginx-ingress-controller-873061567-4n3k2 -n kube-system cat /etc/nginx/nginx.conf`

examples/customization/ssl-dh-param/nginx/default-backend.yaml

@@ -0,0 +1,51 @@
+apiVersion: extensions/v1beta1
+kind: Deployment
+metadata:
+  name: default-http-backend
+  labels:
+    k8s-app: default-http-backend
+  namespace: kube-system
+spec:
+  replicas: 1
+  template:
+    metadata:
+      labels:
+        k8s-app: default-http-backend
+    spec:
+      terminationGracePeriodSeconds: 60
+      containers:
+      - name: default-http-backend
+        # Any image is permissable as long as:
+        # 1. It serves a 404 page at /
+        # 2. It serves 200 on a /healthz endpoint
+        image: gcr.io/google_containers/defaultbackend:1.0
+        livenessProbe:
+          httpGet:
+            path: /healthz
+            port: 8080
+            scheme: HTTP
+          initialDelaySeconds: 30
+          timeoutSeconds: 5
+        ports:
+        - containerPort: 8080
+        resources:
+          limits:
+            cpu: 10m
+            memory: 20Mi
+          requests:
+            cpu: 10m
+            memory: 20Mi
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: default-http-backend
+  namespace: kube-system
+  labels:
+    k8s-app: default-http-backend
+spec:
+  ports:
+  - port: 80
+    targetPort: 8080
+  selector:
+    k8s-app: default-http-backend

examples/customization/ssl-dh-param/nginx/nginx-ingress-controller.yaml

@@ -0,0 +1,53 @@
+apiVersion: extensions/v1beta1
+kind: Deployment
+metadata:
+  name: nginx-ingress-controller
+  labels:
+    k8s-app: nginx-ingress-controller
+  namespace: kube-system
+spec:
+  replicas: 1
+  template:
+    metadata:
+      labels:
+        k8s-app: nginx-ingress-controller
+    spec:
+      # hostNetwork makes it possible to use ipv6 and to preserve the source IP correctly regardless of docker configuration
+      # however, it is not a hard dependency of the nginx-ingress-controller itself and it may cause issues if port 10254 already is taken on the host
+      # that said, since hostPort is broken on CNI (https://github.com/kubernetes/kubernetes/issues/31307) we have to use hostNetwork where CNI is used
+      # like with kubeadm
+      # hostNetwork: true
+      terminationGracePeriodSeconds: 60
+      containers:
+      - image: gcr.io/google_containers/nginx-ingress-controller:0.9.0-beta.3
+        name: nginx-ingress-controller
+        readinessProbe:
+          httpGet:
+            path: /healthz
+            port: 10254
+            scheme: HTTP
+        livenessProbe:
+          httpGet:
+            path: /healthz
+            port: 10254
+            scheme: HTTP
+          initialDelaySeconds: 10
+          timeoutSeconds: 1
+        ports:
+        - containerPort: 80
+          hostPort: 80
+        - containerPort: 443
+          hostPort: 443
+        env:
+          - name: POD_NAME
+            valueFrom:
+              fieldRef:
+                fieldPath: metadata.name
+          - name: POD_NAMESPACE
+            valueFrom:
+              fieldRef:
+                fieldPath: metadata.namespace
+        args:
+        - /nginx-ingress-controller
+        - --default-backend-service=$(POD_NAMESPACE)/default-http-backend
+        - --configmap=$(POD_NAMESPACE)/nginx-load-balancer-conf

examples/customization/ssl-dh-param/nginx/nginx-load-balancer-conf.yaml

@@ -0,0 +1,7 @@
+apiVersion: v1
+data:
+  ssl-dh-param: "kube-system/lb-dhparam"
+kind: ConfigMap
+metadata:
+  name: nginx-load-balancer-conf
+  namespace: kube-system

examples/customization/ssl-dh-param/nginx/ssl-dh-param.yaml

@@ -0,0 +1,8 @@
+apiVersion: v1
+data:
+  dhparam.pem: "...base64 encoded data..."
+kind: Secret
+type: Opaque
+metadata:
+  name: lb-dhparam
+  namespace: kube-system