Config/Annotations: Add ssl-forbid-http and force-ssl-forbid-http

Author: gavinkflam

docs/user-guide/nginx-configuration/annotations-risk.md

@@ -108,9 +108,11 @@
 | Redirect | temporal-redirect | Medium | location |
 | Redirect | temporal-redirect-code | Low | location |
 | Rewrite | app-root | Medium | location |
+| Rewrite | force-ssl-forbid-http | Medium | location |
 | Rewrite | force-ssl-redirect | Medium | location |
 | Rewrite | preserve-trailing-slash | Medium | location |
 | Rewrite | rewrite-target | Medium | ingress |
+| Rewrite | ssl-forbid-http | Low | location |
 | Rewrite | ssl-redirect | Low | location |
 | Rewrite | use-regex | Low | location |
 | SSLCipher | ssl-ciphers | Low | ingress |

docs/user-guide/nginx-configuration/annotations.md

@@ -59,6 +59,7 @@ You can add these Kubernetes annotations to specific Ingress objects to customiz
 |[nginx.ingress.kubernetes.io/cors-expose-headers](#enable-cors)|string|
 |[nginx.ingress.kubernetes.io/cors-allow-credentials](#enable-cors)|"true" or "false"|
 |[nginx.ingress.kubernetes.io/cors-max-age](#enable-cors)|number|
+|[nginx.ingress.kubernetes.io/force-ssl-forbid-http](#server-side-https-enforcement-through-forbidden-errors)|"true" or "false"|
 |[nginx.ingress.kubernetes.io/force-ssl-redirect](#server-side-https-enforcement-through-redirect)|"true" or "false"|
 |[nginx.ingress.kubernetes.io/from-to-www-redirect](#redirect-fromto-www)|"true" or "false"|
 |[nginx.ingress.kubernetes.io/http2-push-preload](#http2-push-preload)|"true" or "false"|
@@ -104,6 +105,7 @@ You can add these Kubernetes annotations to specific Ingress objects to customiz
 |[nginx.ingress.kubernetes.io/session-cookie-path](#cookie-affinity)|string|
 |[nginx.ingress.kubernetes.io/session-cookie-samesite](#cookie-affinity)|string|"None", "Lax" or "Strict"|
 |[nginx.ingress.kubernetes.io/session-cookie-secure](#cookie-affinity)|string|
+|[nginx.ingress.kubernetes.io/ssl-forbid-http](#server-side-https-enforcement-through-forbidden-errors)|"true" or "false"|
 |[nginx.ingress.kubernetes.io/ssl-redirect](#server-side-https-enforcement-through-redirect)|"true" or "false"|
 |[nginx.ingress.kubernetes.io/ssl-passthrough](#ssl-passthrough)|"true" or "false"|
 |[nginx.ingress.kubernetes.io/stream-snippet](#stream-snippet)|string|
@@ -628,6 +630,21 @@ This can be achieved by using the `nginx.ingress.kubernetes.io/force-ssl-redirec
 
 To preserve the trailing slash in the URI with `ssl-redirect`, set `nginx.ingress.kubernetes.io/preserve-trailing-slash: "true"` annotation for that particular resource.
 
+### Server-side HTTPS enforcement through forbidden errors
+
+In certain scenarios, you might prefer to return a 403 Forbidden error response instead of redirecting traffic to the HTTPS port.
+This approach helps prevent misconfigured clients from inadvertently leaking sensitive data over unencrypted connections.
+
+This can be enabled globally using `ssl-forbid-http: "true"` in the [ConfigMap][./configmap.md#ssl-forbid-http].
+
+To configure this feature for specific Ingress resources, you can use the `nginx.ingress.kubernetes.io/ssl-forbid-http: "true"`
+annotation in the particular resource.
+
+When using SSL off-loading outside of the cluster (e.g. AWS ELB), it may be useful to enforce 403 Forbidden errors to HTTP requests
+even when there is no TLS certificate available.
+
+This can be achieved by using the `nginx.ingress.kubernetes.io/force-ssl-forbid-http: "true"` annotation in the particular resource.
+
 ### Redirect from/to www
 
 In some scenarios, it is required to redirect from `www.domain.com` to `domain.com` or vice versa, which way the redirect is performed depends on the configured `host` value in the Ingress object.

docs/user-guide/nginx-configuration/configmap.md

@@ -189,6 +189,8 @@ The following table shows a configuration option's name, type, and the default v
 | [proxy-request-buffering](#proxy-request-buffering)                             | string       | "on"                                                                                                                                                                                                                                                                                                                                                         |                                                                                     |
 | [ssl-redirect](#ssl-redirect)                                                   | bool         | "true"                                                                                                                                                                                                                                                                                                                                                       |                                                                                     |
 | [force-ssl-redirect](#force-ssl-redirect)                                       | bool         | "false"                                                                                                                                                                                                                                                                                                                                                      |                                                                                     |
+| [ssl-forbid-http](#ssl-forbid-http)                                             | bool         | "false"                                                                                                                                                                                                                                                                                                                                                      |                                                                                     |
+| [force-ssl-forbid-http](#force-ssl-forbid-http)                                 | bool         | "false"                                                                                                                                                                                                                                                                                                                                                      |                                                                                     |
 | [denylist-source-range](#denylist-source-range)                                 | []string     | []string{}                                                                                                                                                                                                                                                                                                                                                   |                                                                                     |
 | [whitelist-source-range](#whitelist-source-range)                               | []string     | []string{}                                                                                                                                                                                                                                                                                                                                                   |                                                                                     |
 | [skip-access-log-urls](#skip-access-log-urls)                                   | []string     | []string{}                                                                                                                                                                                                                                                                                                                                                   |                                                                                     |
@@ -1154,6 +1156,18 @@ _**default:**_ "true"
 Sets the global value of redirects (308) to HTTPS if the server has a default TLS certificate (defined in extra-args).
 _**default:**_ "false"
 
+## ssl-forbid-http
+
+Sets the global value of 403 Forbidden errors to HTTP if the server has a TLS certificate (defined in an Ingress rule).
+
+_**default:**_ "false"
+
+## force-ssl-forbid-http
+
+Sets the global value of 403 Forbidden errors to HTTP if the server has a default TLS certificate (defined in extra-args).
+
+_**default:**_ "false"
+
 ## denylist-source-range
 
 Sets the default denylisted IPs for each `server` block. This can be overwritten by an annotation on an Ingress rule.

docs/user-guide/tls.md

@@ -78,21 +78,31 @@ HSTS is enabled by default.
 
 To disable this behavior use `hsts: "false"` in the configuration [ConfigMap][ConfigMap].
 
-## Server-side HTTPS enforcement through redirect
+## Server-side HTTPS enforcement
 
 By default the controller redirects HTTP clients to the HTTPS port
 443 using a 308 Permanent Redirect response if TLS is enabled for that Ingress.
 
-This can be disabled globally using `ssl-redirect: "false"` in the NGINX [config map][ConfigMap],
+This can be disabled globally using `ssl-redirect: "false"` in the [config map][ConfigMap],
 or per-Ingress with the `nginx.ingress.kubernetes.io/ssl-redirect: "false"`
 annotation in the particular resource.
 
+In certain scenarios, you might prefer to return a 403 Forbidden error response instead of redirecting traffic to the HTTPS port.
+This approach helps prevent misconfigured clients from inadvertently leaking sensitive data over unencrypted connections.
+
+This can be enabled globally using `ssl-forbid-http: "true"` in the [config map][ConfigMap],
+or per-Ingress with the `nginx.ingress.kubernetes.io/ssl-forbid-http: "true"` annotation in the particular resource.
+
 !!! tip
     When using SSL offloading outside of cluster (e.g. AWS ELB) it may be useful to enforce a
     redirect to HTTPS even when there is no TLS certificate available.
     This can be achieved by using the `nginx.ingress.kubernetes.io/force-ssl-redirect: "true"`
     annotation in the particular resource.
 
+    Similarly, you can enforce 403 Forbidden errors to HTTP requests using the
+    `nginx.ingress.kubernetes.io/force-ssl-forbid-http: "true"` annotation in the particular
+    resource.
+
 ## Automated Certificate Management with cert-manager
 
 [cert-manager] automatically requests missing or expired certificates from a range of 

internal/ingress/annotations/rewrite/main.go

@@ -32,6 +32,8 @@ const (
 	sslRedirectAnnotation           = "ssl-redirect"
 	preserveTrailingSlashAnnotation = "preserve-trailing-slash"
 	forceSSLRedirectAnnotation      = "force-ssl-redirect"
+	sslForbidHTTPAnnotation         = "ssl-forbid-http"
+	forceSSLForbidHTTPAnnotation    = "force-ssl-forbid-http"
 	useRegexAnnotation              = "use-regex"
 	appRootAnnotation               = "app-root"
 )
@@ -64,6 +66,18 @@ var rewriteAnnotations = parser.Annotation{
 			Risk:          parser.AnnotationRiskMedium,
 			Documentation: `This annotation forces the redirection to HTTPS even if the Ingress is not TLS Enabled`,
 		},
+		sslForbidHTTPAnnotation: {
+			Validator:     parser.ValidateBool,
+			Scope:         parser.AnnotationScopeLocation,
+			Risk:          parser.AnnotationRiskLow,
+			Documentation: `This annotation defines if the location section should forbid HTTP requests`,
+		},
+		forceSSLForbidHTTPAnnotation: {
+			Validator:     parser.ValidateBool,
+			Scope:         parser.AnnotationScopeLocation,
+			Risk:          parser.AnnotationRiskMedium,
+			Documentation: `This annotation forces the forbidden error to HTTP even if the Ingress is not TLS Enabled`,
+		},
 		useRegexAnnotation: {
 			Validator: parser.ValidateBool,
 			Scope:     parser.AnnotationScopeLocation,
@@ -88,6 +102,10 @@ type Config struct {
 	SSLRedirect bool `json:"sslRedirect"`
 	// ForceSSLRedirect indicates if the location section is accessible SSL only
 	ForceSSLRedirect bool `json:"forceSSLRedirect"`
+	// SSLForbidHTTP indicates if the location section is accessible SSL only
+	SSLForbidHTTP bool `json:"sslForbidHTTP"`
+	// ForceSSLForbidHTTP indicates if the location section is accessible SSL only
+	ForceSSLForbidHTTP bool `json:"forceSSLForbidHTTP"`
 	// PreserveTrailingSlash indicates if the trailing slash should be kept during a tls redirect
 	PreserveTrailingSlash bool `json:"preserveTrailingSlash"`
 	// AppRoot defines the Application Root that the Controller must redirect if it's in '/' context
@@ -113,6 +131,12 @@ func (r1 *Config) Equal(r2 *Config) bool {
 	if r1.ForceSSLRedirect != r2.ForceSSLRedirect {
 		return false
 	}
+	if r1.SSLForbidHTTP != r2.SSLForbidHTTP {
+		return false
+	}
+	if r1.ForceSSLForbidHTTP != r2.ForceSSLForbidHTTP {
+		return false
+	}
 	if r1.AppRoot != r2.AppRoot {
 		return false
 	}
@@ -172,6 +196,22 @@ func (a rewrite) Parse(ing *networking.Ingress) (interface{}, error) {
 		config.ForceSSLRedirect = a.r.GetDefaultBackend().ForceSSLRedirect
 	}
 
+	config.SSLForbidHTTP, err = parser.GetBoolAnnotation(sslForbidHTTPAnnotation, ing, a.annotationConfig.Annotations)
+	if err != nil {
+		if errors.IsValidationError(err) {
+			klog.Warningf("%s is invalid, defaulting to '%t'", sslForbidHTTPAnnotation, a.r.GetDefaultBackend().SSLForbidHTTP)
+		}
+		config.SSLForbidHTTP = a.r.GetDefaultBackend().SSLForbidHTTP
+	}
+
+	config.ForceSSLForbidHTTP, err = parser.GetBoolAnnotation(forceSSLForbidHTTPAnnotation, ing, a.annotationConfig.Annotations)
+	if err != nil {
+		if errors.IsValidationError(err) {
+			klog.Warningf("%s is invalid, defaulting to '%t'", forceSSLForbidHTTPAnnotation, a.r.GetDefaultBackend().ForceSSLForbidHTTP)
+		}
+		config.ForceSSLForbidHTTP = a.r.GetDefaultBackend().ForceSSLForbidHTTP
+	}
+
 	config.UseRegex, err = parser.GetBoolAnnotation(useRegexAnnotation, ing, a.annotationConfig.Annotations)
 	if err != nil {
 		if errors.IsValidationError(err) {

internal/ingress/annotations/rewrite/main_test.go

@@ -213,6 +213,70 @@ func TestForceSSLRedirect(t *testing.T) {
 	}
 }
 
+func TestSSLForbidHTTP(t *testing.T) {
+	ing := buildIngress()
+
+	i, err := NewParser(mockBackend{}).Parse(ing)
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+	forbid, ok := i.(*Config)
+	if !ok {
+		t.Errorf("expected a Forbid type")
+	}
+	if forbid.SSLForbidHTTP {
+		t.Errorf("Expected false but returned true")
+	}
+
+	data := map[string]string{}
+	data[parser.GetAnnotationWithPrefix("ssl-forbid-http")] = "true"
+	ing.SetAnnotations(data)
+
+	i, err = NewParser(mockBackend{}).Parse(ing)
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+	forbid, ok = i.(*Config)
+	if !ok {
+		t.Errorf("expected a Forbid type")
+	}
+	if !forbid.SSLForbidHTTP {
+		t.Errorf("Expected true but returned false")
+	}
+}
+
+func TestForceSSLForbidHTTP(t *testing.T) {
+	ing := buildIngress()
+
+	i, err := NewParser(mockBackend{}).Parse(ing)
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+	forbid, ok := i.(*Config)
+	if !ok {
+		t.Errorf("expected a Forbid type")
+	}
+	if forbid.ForceSSLForbidHTTP {
+		t.Errorf("Expected false but returned true")
+	}
+
+	data := map[string]string{}
+	data[parser.GetAnnotationWithPrefix("force-ssl-forbid-http")] = "true"
+	ing.SetAnnotations(data)
+
+	i, err = NewParser(mockBackend{}).Parse(ing)
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+	forbid, ok = i.(*Config)
+	if !ok {
+		t.Errorf("expected a Forbid type")
+	}
+	if !forbid.ForceSSLForbidHTTP {
+		t.Errorf("Expected true but returned false")
+	}
+}
+
 func TestAppRoot(t *testing.T) {
 	ap := NewParser(mockBackend{redirect: true})
 

internal/ingress/controller/template/template.go

@@ -435,6 +435,8 @@ func locationConfigForLua(l, a interface{}) string {
 		force_ssl_redirect = string_to_bool(ngx.var.force_ssl_redirect),
 	    ssl_redirect = string_to_bool(ngx.var.ssl_redirect),
 	    force_no_ssl_redirect = string_to_bool(ngx.var.force_no_ssl_redirect),
+	    force_ssl_forbid_http = string_to_bool(ngx.var.force_ssl_forbid_http),
+	    ssl_forbid_http = string_to_bool(ngx.var.ssl_forbid_http),
 	    preserve_trailing_slash = string_to_bool(ngx.var.preserve_trailing_slash),
 	    use_port_in_redirects = string_to_bool(ngx.var.use_port_in_redirects),
 	*/
@@ -443,12 +445,16 @@ func locationConfigForLua(l, a interface{}) string {
 	    set $force_ssl_redirect "%t";
 	    set $ssl_redirect "%t";
 	    set $force_no_ssl_redirect "%t";
+	    set $force_ssl_forbid_http "%t";
+	    set $ssl_forbid_http "%t";
 	    set $preserve_trailing_slash "%t";
 	    set $use_port_in_redirects "%t";
 	`,
 		location.Rewrite.ForceSSLRedirect,
 		location.Rewrite.SSLRedirect,
 		isLocationInLocationList(l, all.Cfg.NoTLSRedirectLocations),
+		location.Rewrite.ForceSSLForbidHTTP,
+		location.Rewrite.SSLForbidHTTP,
 		location.Rewrite.PreserveTrailingSlash,
 		location.UsePortInRedirects,
 	)

internal/ingress/defaults/main.go

@@ -126,6 +126,13 @@ type Backend struct {
 	// This is useful if doing SSL offloading outside of cluster eg AWS ELB
 	ForceSSLRedirect bool `json:"force-ssl-redirect"`
 
+	// Enables or disables forbidden errors (403) to HTTP
+	SSLForbidHTTP bool `json:"ssl-forbid-http"`
+
+	// Enables or disables forbidden errors (403) to HTTP even without TLS cert
+	// This is useful if doing SSL offloading outside of cluster eg AWS ELB
+	ForceSSLForbidHTTP bool `json:"force-ssl-forbid-http"`
+
 	// Enables or disables the specification of port in redirects
 	// Default: false
 	UsePortInRedirects bool `json:"use-port-in-redirects"`

rootfs/etc/nginx/lua/lua_ingress.lua

@@ -62,6 +62,18 @@ local function randomseed()
   math.randomseed(seed)
 end
 
+local function forbid_http(location_config)
+  if location_config.force_ssl_forbid_http and ngx.var.pass_access_scheme == "http" then
+    return true
+  end
+
+  if ngx.var.pass_access_scheme ~= "http" then
+    return false
+  end
+
+  return location_config.ssl_forbid_http and certificate_configured_for_current_request()
+end
+
 local function redirect_to_https(location_config)
   if location_config.force_no_ssl_redirect then
     return false
@@ -115,6 +127,8 @@ function _M.rewrite()
     force_ssl_redirect = string_to_bool(ngx.var.force_ssl_redirect),
     ssl_redirect = string_to_bool(ngx.var.ssl_redirect),
     force_no_ssl_redirect = string_to_bool(ngx.var.force_no_ssl_redirect),
+    force_ssl_forbid_http = string_to_bool(ngx.var.force_ssl_forbid_http),
+    ssl_forbid_http = string_to_bool(ngx.var.ssl_forbid_http),
     preserve_trailing_slash = string_to_bool(ngx.var.preserve_trailing_slash),
     use_port_in_redirects = string_to_bool(ngx.var.use_port_in_redirects),
   }
@@ -154,6 +168,10 @@ function _M.rewrite()
     ngx.var.pass_port = 443
   end
 
+  if forbid_http(location_config) then
+    ngx.exit(ngx.HTTP_FORBIDDEN)
+  end
+
   if redirect_to_https(location_config) then
     local request_uri = ngx.var.request_uri
     -- do not append a trailing slash on redirects unless enabled by annotations

test/data/cleanConf.expected.conf

@@ -115,6 +115,8 @@ http {
 					force_ssl_redirect = false,
 					ssl_redirect = false,
 					force_no_ssl_redirect = false,
+					force_ssl_forbid_http = false,
+					ssl_forbid_http = false,
 					use_port_in_redirects = false,
 				})
 				balancer.rewrite()

test/data/cleanConf.src.conf

@@ -158,6 +158,8 @@ lua_shared_dict ocsp_response_cache 5M;
 		force_ssl_redirect = false,
 		ssl_redirect = false,
 		force_no_ssl_redirect = false,
+		force_ssl_forbid_http = false,
+		ssl_forbid_http = false,
 		use_port_in_redirects = false,
 	})
                 balancer.rewrite()