Add default headers to webserver responses (#97784)

* Add default headers to webserver responses

* Set default server header

* Fix other tests

homeassistant/components/http/__init__.py

@@ -53,6 +53,7 @@
 )
 from .cors import setup_cors
 from .forwarded import async_setup_forwarded
+from .headers import setup_headers
 from .request_context import current_request, setup_request_context
 from .security_filter import setup_security_filter
 from .static import CACHE_HEADERS, CachingStaticResource
@@ -69,6 +70,7 @@
 CONF_SSL_KEY: Final = "ssl_key"
 CONF_CORS_ORIGINS: Final = "cors_allowed_origins"
 CONF_USE_X_FORWARDED_FOR: Final = "use_x_forwarded_for"
+CONF_USE_X_FRAME_OPTIONS: Final = "use_x_frame_options"
 CONF_TRUSTED_PROXIES: Final = "trusted_proxies"
 CONF_LOGIN_ATTEMPTS_THRESHOLD: Final = "login_attempts_threshold"
 CONF_IP_BAN_ENABLED: Final = "ip_ban_enabled"
@@ -118,6 +120,7 @@
             vol.Optional(CONF_SSL_PROFILE, default=SSL_MODERN): vol.In(
                 [SSL_INTERMEDIATE, SSL_MODERN]
             ),
+            vol.Optional(CONF_USE_X_FRAME_OPTIONS, default=True): cv.boolean,
         }
     ),
 )
@@ -136,6 +139,7 @@ class ConfData(TypedDict, total=False):
     ssl_key: str
     cors_allowed_origins: list[str]
     use_x_forwarded_for: bool
+    use_x_frame_options: bool
     trusted_proxies: list[IPv4Network | IPv6Network]
     login_attempts_threshold: int
     ip_ban_enabled: bool
@@ -180,6 +184,7 @@ async def async_setup(hass: HomeAssistant, config: ConfigType) -> bool:
     ssl_key = conf.get(CONF_SSL_KEY)
     cors_origins = conf[CONF_CORS_ORIGINS]
     use_x_forwarded_for = conf.get(CONF_USE_X_FORWARDED_FOR, False)
+    use_x_frame_options = conf[CONF_USE_X_FRAME_OPTIONS]
     trusted_proxies = conf.get(CONF_TRUSTED_PROXIES) or []
     is_ban_enabled = conf[CONF_IP_BAN_ENABLED]
     login_threshold = conf[CONF_LOGIN_ATTEMPTS_THRESHOLD]
@@ -200,6 +205,7 @@ async def async_setup(hass: HomeAssistant, config: ConfigType) -> bool:
         use_x_forwarded_for=use_x_forwarded_for,
         login_threshold=login_threshold,
         is_ban_enabled=is_ban_enabled,
+        use_x_frame_options=use_x_frame_options,
     )
 
     async def stop_server(event: Event) -> None:
@@ -331,6 +337,7 @@ async def async_initialize(
         use_x_forwarded_for: bool,
         login_threshold: int,
         is_ban_enabled: bool,
+        use_x_frame_options: bool,
     ) -> None:
         """Initialize the server."""
         self.app[KEY_HASS] = self.hass
@@ -348,6 +355,7 @@ async def async_initialize(
 
         await async_setup_auth(self.hass, self.app)
 
+        setup_headers(self.app, use_x_frame_options)
         setup_cors(self.app, cors_origins)
 
         if self.ssl_certificate:

homeassistant/components/http/headers.py

@@ -0,0 +1,32 @@
+"""Middleware that helps with the control of headers in our responses."""
+from __future__ import annotations
+
+from collections.abc import Awaitable, Callable
+
+from aiohttp.web import Application, Request, StreamResponse, middleware
+
+from homeassistant.core import callback
+
+
+@callback
+def setup_headers(app: Application, use_x_frame_options: bool) -> None:
+    """Create headers middleware for the app."""
+
+    @middleware
+    async def headers_middleware(
+        request: Request, handler: Callable[[Request], Awaitable[StreamResponse]]
+    ) -> StreamResponse:
+        """Process request and add headers to the responses."""
+        response = await handler(request)
+        response.headers["Referrer-Policy"] = "no-referrer"
+        response.headers["X-Content-Type-Options"] = "nosniff"
+
+        # Set an empty server header, to prevent aiohttp of setting one.
+        response.headers["Server"] = ""
+
+        if use_x_frame_options:
+            response.headers["X-Frame-Options"] = "SAMEORIGIN"
+
+        return response
+
+    app.middlewares.append(headers_middleware)

tests/components/http/test_headers.py

@@ -0,0 +1,44 @@
+"""Test headers middleware."""
+from http import HTTPStatus
+
+from aiohttp import web
+
+from homeassistant.components.http.headers import setup_headers
+
+from tests.typing import ClientSessionGenerator
+
+
+async def mock_handler(request):
+    """Return OK."""
+    return web.Response(text="OK")
+
+
+async def test_headers_added(aiohttp_client: ClientSessionGenerator) -> None:
+    """Test that headers are being added on each request."""
+    app = web.Application()
+    app.router.add_get("/", mock_handler)
+
+    setup_headers(app, use_x_frame_options=True)
+
+    mock_api_client = await aiohttp_client(app)
+    resp = await mock_api_client.get("/")
+
+    assert resp.status == HTTPStatus.OK
+    assert resp.headers["Referrer-Policy"] == "no-referrer"
+    assert resp.headers["Server"] == ""
+    assert resp.headers["X-Content-Type-Options"] == "nosniff"
+    assert resp.headers["X-Frame-Options"] == "SAMEORIGIN"
+
+
+async def test_allow_framing(aiohttp_client: ClientSessionGenerator) -> None:
+    """Test that we allow framing when disabled."""
+    app = web.Application()
+    app.router.add_get("/", mock_handler)
+
+    setup_headers(app, use_x_frame_options=False)
+
+    mock_api_client = await aiohttp_client(app)
+    resp = await mock_api_client.get("/")
+
+    assert resp.status == HTTPStatus.OK
+    assert "X-Frame-Options" not in resp.headers

tests/scripts/test_check_config.py

@@ -117,6 +117,7 @@ def test_secrets(mock_is_file, event_loop, mock_hass_config_yaml: None) -> None:
         "login_attempts_threshold": -1,
         "server_port": 8123,
         "ssl_profile": "modern",
+        "use_x_frame_options": True,
     }
     assert res["secret_cache"] == {
         get_test_config_dir("secrets.yaml"): {"http_pw": "http://google.com"}