MINOR: add client-strict-sni annotation

When enbaled HAProxy will only accept TLS client connections where
the provided SNI matchs an existing certificate. Otherwise the default
certificate will be provided when the provided SNI does not match.

Author: Mo3m3n

controller/handler/https.go

@@ -31,14 +31,15 @@ import (
 )
 
 type HTTPS struct {
-	Enabled  bool
-	IPv4     bool
-	IPv6     bool
-	Port     int64
-	AddrIPv4 string
-	AddrIPv6 string
-	CertDir  string
-	Alpn     string
+	Enabled   bool
+	IPv4      bool
+	IPv6      bool
+	strictSNI bool
+	Port      int64
+	AddrIPv4  string
+	AddrIPv6  string
+	CertDir   string
+	alpn      string
 }
 
 func (h HTTPS) bindList(passhthrough bool) (binds []models.Bind) {
@@ -147,12 +148,15 @@ func (h HTTPS) Update(k store.K8s, cfg *config.ControllerCfg, api api.HAProxyCli
 	}
 
 	// Fetch tls-alpn value for when SSL offloading is enabled
-	h.Alpn = annotations.String("tls-alpn", k.ConfigMaps.Main.Annotations)
+	h.alpn = annotations.String("tls-alpn", k.ConfigMaps.Main.Annotations)
+
+	h.strictSNI, err = annotations.Bool("client-strict-sni", k.ConfigMaps.Main.Annotations)
+	logger.Error(err)
 
 	// ssl-offload
 	if cfg.Certificates.FrontendCertsEnabled() {
 		if !cfg.HTTPS {
-			logger.Panic(api.FrontendEnableSSLOffload(cfg.FrontHTTPS, h.CertDir, h.Alpn))
+			logger.Panic(api.FrontendEnableSSLOffload(cfg.FrontHTTPS, h.CertDir, h.alpn, h.strictSNI))
 			cfg.HTTPS = true
 			reload = true
 			logger.Debug("SSLOffload enabeld, reload required")
@@ -253,7 +257,7 @@ func (h HTTPS) toggleSSLPassthrough(passthrough bool, cfg *config.ControllerCfg,
 		}
 	}
 	if cfg.HTTPS {
-		logger.Panic(api.FrontendEnableSSLOffload(cfg.FrontHTTPS, h.CertDir, h.Alpn))
+		logger.Panic(api.FrontendEnableSSLOffload(cfg.FrontHTTPS, h.CertDir, h.alpn, h.strictSNI))
 	}
 	return nil
 }

controller/handler/tcp-services.go

@@ -142,7 +142,7 @@ func (t TCPServices) createTCPFrontend(api api.HAProxyClient, frontendName, bind
 		}))
 	}
 	if sslOffload {
-		errors.Add(api.FrontendEnableSSLOffload(frontend.Name, t.CertDir, ""))
+		errors.Add(api.FrontendEnableSSLOffload(frontend.Name, t.CertDir, "", false))
 	}
 	if errors.Result() != nil {
 		err = fmt.Errorf("error configuring tcp frontend: %w", err)
@@ -159,7 +159,7 @@ func (t TCPServices) updateTCPFrontend(k store.K8s, cfg *config.ControllerCfg, a
 		return
 	}
 	if !binds[0].Ssl && p.sslOffload {
-		err = api.FrontendEnableSSLOffload(frontend.Name, t.CertDir, "")
+		err = api.FrontendEnableSSLOffload(frontend.Name, t.CertDir, "", false)
 		if err != nil {
 			err = fmt.Errorf("failed to enable SSL offload: %w", err)
 			return

controller/haproxy/api/api.go

@@ -37,7 +37,7 @@ type HAProxyClient interface {
 	FrontendsGet() (models.Frontends, error)
 	FrontendGet(frontendName string) (models.Frontend, error)
 	FrontendEdit(frontend models.Frontend) error
-	FrontendEnableSSLOffload(frontendName string, certDir string, alpn string) (err error)
+	FrontendEnableSSLOffload(frontendName string, certDir string, alpn string, strictSNI bool) (err error)
 	FrontendDisableSSLOffload(frontendName string) (err error)
 	FrontendBindsGet(frontend string) (models.Binds, error)
 	FrontendBindCreate(frontend string, bind models.Bind) error

controller/haproxy/api/frontend.go

@@ -51,7 +51,7 @@ func (c *clientNative) FrontendEdit(frontend models.Frontend) error {
 	return c.nativeAPI.Configuration.EditFrontend(frontend.Name, &frontend, c.activeTransaction, 0)
 }
 
-func (c *clientNative) FrontendEnableSSLOffload(frontendName string, certDir string, alpn string) (err error) {
+func (c *clientNative) FrontendEnableSSLOffload(frontendName string, certDir string, alpn string, strictSNI bool) (err error) {
 	binds, err := c.FrontendBindsGet(frontendName)
 	if err != nil {
 		return err
@@ -61,6 +61,7 @@ func (c *clientNative) FrontendEnableSSLOffload(frontendName string, certDir str
 		bind.SslCertificate = certDir
 		if alpn != "" {
 			bind.Alpn = alpn
+			bind.StrictSni = strictSNI
 		}
 		err = c.FrontendBindEdit(frontendName, *bind)
 	}
@@ -81,6 +82,7 @@ func (c *clientNative) FrontendDisableSSLOffload(frontendName string) (err error
 		bind.Verify = ""
 		bind.SslCertificate = ""
 		bind.Alpn = ""
+		bind.StrictSni = false
 		err = c.FrontendBindEdit(frontendName, *bind)
 	}
 	if err != nil {

documentation/README.md

@@ -24,6 +24,7 @@ This is autogenerated from [doc.yaml](doc.yaml). Description can be found in [ge
 | [clean-certs](#clean-certs) | [bool](#bool) | "true" |  |:large_blue_circle:|:white_circle:|:white_circle:|
 | [client-ca](#authentication) | string |  | ssl-offloading |:large_blue_circle:|:white_circle:|:white_circle:|
 | [client-crt-optional](#authentication) | [bool](#bool) | "false" | client-ca |:large_blue_circle:|:white_circle:|:white_circle:|
+| [client-strict-sni](#ssl-offloading) | [bool](#bool) | "false" | client-ca |:large_blue_circle:|:white_circle:|:white_circle:|
 | [cors-enable](#CORS) | [bool](#bool) | "false" |  |:large_blue_circle:|:large_blue_circle:|:white_circle:|
 | [cors-allow-origin](#CORS) | string | "*" | cors-enable |:large_blue_circle:|:large_blue_circle:|:white_circle:|
 | [cors-allow-methods](#CORS) | string | "*" | cors-enable |:large_blue_circle:|:large_blue_circle:|:white_circle:|
@@ -1513,6 +1514,24 @@ src-ip-header: "True-Client-IP"
 - Certificates can be defined in Ingress object: `spec.tls[].secretName`
 
 
+##### `client-strict-sni`
+
+  If enabled, HAProxy will only accept TLS client connections where the provided SNI matchs an existing certificate.
+  If disabled HAProxy will service the default certificate when the provided SNI does not match.
+
+  Available on:  `configmap`
+
+Possible values:
+
+- true
+- false `default`
+
+Example:
+
+```yaml
+client-strict-sni: true
+```
+
 ##### `ssl-certificate`
 
   Sets the name of the Kubernetes secret that contains both the TLS key and certificate.

documentation/doc.yaml

@@ -614,6 +614,22 @@ annotations:
     version_min: "1.6"
     example:
       - "client-crt-optional: true"
+  - title: client-strict-sni
+    type: bool
+    group: ssl-offloading
+    dependencies: client-ca
+    default: "false"
+    description:
+      - If enabled, HAProxy will only accept TLS client connections where the provided SNI matchs an existing certificate.
+      - If disabled HAProxy will service the default certificate when the provided SNI does not match.
+    values:
+      - "true"
+      - "false"
+    applies_to:
+      - configmap
+    version_min: "1.7"
+    example:
+      - "client-strict-sni: true"
   - title: cors-enable
     type: bool
     group: CORS