fix(admin): compare the request origin against an origin (#2610)

fluxer_admin/src/config/mod.rs

@@ -129,6 +129,11 @@ impl AdminConfig {
     pub fn secure_cookies(&self) -> bool {
         self.admin_endpoint.starts_with("https://")
     }
+
+    pub fn admin_origin(&self) -> Option<String> {
+        let origin = url::Url::parse(&self.admin_endpoint).ok()?.origin();
+        origin.is_tuple().then(|| origin.ascii_serialization())
+    }
 }
 
 impl RuntimeEnv {
@@ -202,6 +207,7 @@ mod tests {
             unsafe { env::remove_var(name) };
         }
         unsafe { env::remove_var("FLUXER_PUBLIC_PORT") };
+        unsafe { env::remove_var("FLUXER_PUBLIC_ORIGIN") };
         unsafe { env::set_var("FLUXER_ADMIN_SECRET_KEY_BASE", "test-secret") };
         for (name, value) in vars {
             unsafe { env::set_var(name, value) };
@@ -350,7 +356,7 @@ mod tests {
             ("FLUXER_BASE_DOMAIN", "fluxer.example"),
             ("FLUXER_PUBLIC_PORT", "19080"),
             ("FLUXER_ADMIN_ENDPOINT", "http://fluxer.example/admin"),
-            ("FLUXER_APP_ENDPOINT", "http://fluxer.example:19080"),
+            ("FLUXER_APP_ENDPOINT", "http://fluxer.example"),
             ("FLUXER_MEDIA_ENDPOINT", "http://fluxer.example/media"),
             ("FLUXER_STATIC_CDN_ENDPOINT", "https://cdn.example.net"),
             (

fluxer_admin/src/middleware/csrf.rs

@@ -27,7 +27,6 @@ pub async fn csrf_protection(
 ) -> Response {
     let config = state.config();
     let secret = config.secret_key_base.clone();
-    let admin_endpoint = config.admin_endpoint.clone();
     let secure_cookies = config.secure_cookies();
 
     let user_id = request
@@ -50,7 +49,7 @@ pub async fn csrf_protection(
             .iter()
             .any(|suffix| path.ends_with(suffix));
         if !is_ignored {
-            if !is_same_site_request(&request, &admin_endpoint) {
+            if !is_same_site_request(&request, config.admin_origin().as_deref()) {
                 return StatusCode::FORBIDDEN.into_response();
             }
             let header_token = extract_csrf_header(&request);
@@ -167,7 +166,7 @@ async fn extract_csrf_from_form_body(
     Ok((request, token))
 }
 
-fn is_same_site_request(request: &Request, admin_endpoint: &str) -> bool {
+fn is_same_site_request(request: &Request, admin_origin: Option<&str>) -> bool {
     if let Some(site) = request
         .headers()
         .get("sec-fetch-site")
@@ -180,7 +179,7 @@ fn is_same_site_request(request: &Request, admin_endpoint: &str) -> bool {
         .get(header::ORIGIN)
         .and_then(|value| value.to_str().ok())
     {
-        Some(origin) => origin == admin_endpoint,
+        Some(origin) => admin_origin.is_some_and(|expected| origin == expected),
         None => true,
     }
 }
@@ -275,6 +274,98 @@ mod tests {
         );
     }
 
+    async fn action_status(admin_endpoint: &str, origin: &str) -> StatusCode {
+        let state = state_with_admin_endpoint(admin_endpoint);
+        let app = Router::new()
+            .route("/", get(|| async { "ok" }).post(|| async { "ok" }))
+            .layer(from_fn_with_state(state, csrf_protection));
+        let issued = app
+            .clone()
+            .oneshot(Request::builder().uri("/").body(Body::empty()).unwrap())
+            .await
+            .expect("router responds");
+        let cookie = issued
+            .headers()
+            .get_all(header::SET_COOKIE)
+            .iter()
+            .filter_map(|value| value.to_str().ok())
+            .filter_map(|value| value.split(';').next())
+            .find(|pair| pair.contains("csrf_token=") && !pair.ends_with('='))
+            .expect("a csrf cookie is issued")
+            .to_owned();
+        let token = cookie.split_once('=').expect("a cookie value").1.to_owned();
+        let response = app
+            .oneshot(
+                Request::builder()
+                    .method(Method::POST)
+                    .uri("/")
+                    .header(header::COOKIE, cookie.as_str())
+                    .header(header::ORIGIN, origin)
+                    .header(CSRF_HEADER_NAME, token.as_str())
+                    .body(Body::empty())
+                    .unwrap(),
+            )
+            .await
+            .expect("router responds");
+        response.status()
+    }
+
+    #[tokio::test]
+    async fn a_matching_origin_passes_the_same_site_check() {
+        let status = action_status(
+            "https://admin.example.test/admin",
+            "https://admin.example.test",
+        )
+        .await;
+        assert_eq!(status, StatusCode::OK);
+    }
+
+    #[tokio::test]
+    async fn a_matching_origin_on_a_non_default_port_passes_the_same_site_check() {
+        let status = action_status(
+            "https://admin.example.test:19080/admin",
+            "https://admin.example.test:19080",
+        )
+        .await;
+        assert_eq!(status, StatusCode::OK);
+    }
+
+    #[tokio::test]
+    async fn a_foreign_origin_fails_the_same_site_check() {
+        let status = action_status(
+            "https://admin.example.test:19080/admin",
+            "https://evil.example.test:19080",
+        )
+        .await;
+        assert_eq!(status, StatusCode::FORBIDDEN);
+    }
+
+    #[tokio::test]
+    async fn another_port_on_the_admin_host_fails_the_same_site_check() {
+        let status = action_status(
+            "https://admin.example.test:19080/admin",
+            "https://admin.example.test",
+        )
+        .await;
+        assert_eq!(status, StatusCode::FORBIDDEN);
+    }
+
+    #[tokio::test]
+    async fn an_unparseable_admin_endpoint_fails_closed() {
+        let status = action_status("not-an-endpoint", "https://admin.example.test").await;
+        assert_eq!(status, StatusCode::FORBIDDEN);
+    }
+
+    #[tokio::test]
+    async fn an_explicit_default_port_matches_a_portless_origin() {
+        let status = action_status(
+            "https://admin.example.test:443/admin",
+            "https://admin.example.test",
+        )
+        .await;
+        assert_eq!(status, StatusCode::OK);
+    }
+
     #[test]
     fn oauth2_callback_is_exempt() {
         let exempt = IGNORED_PATH_SUFFIXES

fluxer_admin/tests/csrf_legacy_cookie.rs

@@ -18,6 +18,7 @@ use tower::ServiceExt;
 const SECRET_KEY: &str = "legacy-csrf-cookie-test-secret";
 const ADMIN_ORIGIN: &str = "https://admin.example.test";
 const LEGACY_HEX_TOKEN: &str = "8f14e45fceea167a5a36dedd4bea25438f14e45fceea167a5a36dedd4bea2543";
+const CREATED_KEY_SECRET: &str = "fa_1900000000000000001_OneTimeSecretForTests";
 
 struct TestApp {
     router: Router,
@@ -128,6 +129,10 @@ async fn load_page(app: &TestApp, cookie: &str) -> (String, String) {
     let body = to_bytes(response.into_body(), usize::MAX).await.unwrap();
     let text = String::from_utf8(body.to_vec()).unwrap();
     assert_eq!(status, StatusCode::OK, "{text}");
+    assert!(
+        text.contains("AdminUser"),
+        "the page did not render the admin the mock API returns"
+    );
     let cookie_token = host_csrf_cookie(&headers)
         .unwrap_or_else(|| panic!("no __Host-csrf_token in Set-Cookie: {headers:?}"));
     let page_token = form_csrf_value(&text).expect("no _csrf hidden input rendered");
@@ -166,7 +171,16 @@ async fn submit_action(app: &TestApp, cookie: &str, form_token: &str) -> StatusC
         )
         .await
         .unwrap();
-    response.status()
+    let status = response.status();
+    let body = to_bytes(response.into_body(), usize::MAX).await.unwrap();
+    let text = String::from_utf8(body.to_vec()).unwrap();
+    if status == StatusCode::OK {
+        assert!(
+            text.contains(CREATED_KEY_SECRET),
+            "the action did not render the key the mock API creates"
+        );
+    }
+    status
 }
 
 fn host_csrf_cookie(headers: &HeaderMap) -> Option<String> {
@@ -207,11 +221,11 @@ async fn spawn_mock_api() -> String {
 
 async fn mock_api(method: Method, uri: Uri) -> Response {
     match (method, uri.path()) {
-        (Method::GET, "/admin/users/me") => Json(json!({ "user": admin_user() })).into_response(),
+        (Method::GET, "/admin/users/@me") => Json(json!({ "user": admin_user() })).into_response(),
         (Method::GET, "/admin/api-keys") => Json(json!([])).into_response(),
         (Method::POST, "/admin/api-keys") => Json(json!({
             "key_id": "1900000000000000001",
-            "key": "fa_1900000000000000001_OneTimeSecretForTests",
+            "key": CREATED_KEY_SECRET,
             "name": "Legacy Cookie Key",
             "created_at": "2026-07-10T15:00:00.000Z",
             "expires_at": null,