feat: better security with <script nonce="">

Cargo.toml

@@ -36,6 +36,7 @@ url = "2.3.1"
 actix-governor = "0.5.0"
 governor = "0.6.3"
 lazy_static = "1.4.0"
+actix-web-lab = "0.20.2"
 
 [profile.release]
 strip = "symbols"

snippet/auth.html.snippet

@@ -6,4 +6,4 @@
           <br />
           <input id="password" name="password" type="password" />
         </div>
-        <script src="/static/auth-hide.js"></script>
+        <script nonce="{script_nonce}" src="/static/auth-hide.js"></script>

src/main.rs

@@ -6,6 +6,7 @@ mod file_info;
 mod mime_relations;
 mod multipart;
 mod rate_limit;
+mod script_nonce;
 mod template;
 mod upload;
 
@@ -14,22 +15,19 @@ use actix_files::Files;
 use actix_governor::{Governor, GovernorConfigBuilder};
 use actix_web::{
     http::header::{
-        HeaderName, CONTENT_SECURITY_POLICY, PERMISSIONS_POLICY, REFERRER_POLICY,
-        X_CONTENT_TYPE_OPTIONS, X_FRAME_OPTIONS, X_XSS_PROTECTION,
+        HeaderName, PERMISSIONS_POLICY, REFERRER_POLICY, X_CONTENT_TYPE_OPTIONS, X_FRAME_OPTIONS,
+        X_XSS_PROTECTION,
     },
     middleware::{self, Condition, DefaultHeaders},
     web::{self, Data},
     App, Error, HttpResponse, HttpServer,
 };
+use actix_web_lab::middleware::from_fn;
 use env_logger::Env;
 use sqlx::postgres::PgPool;
 use std::env;
 use tokio::sync::mpsc::channel;
 
-const DEFAULT_CONTENT_SECURITY_POLICY: (HeaderName, &str) = (
-    CONTENT_SECURITY_POLICY,
-    "default-src 'none'; connect-src 'self'; img-src 'self'; media-src 'self'; font-src 'self'; script-src 'self'; style-src 'self'; object-src 'none'; base-uri 'self'; frame-src 'none'; frame-ancestors 'none'; form-action 'self';"
-);
 #[allow(clippy::declare_interior_mutable_const)]
 const DEFAULT_PERMISSIONS: (HeaderName, &str) = (
     PERMISSIONS_POLICY,
@@ -85,7 +83,6 @@ async fn main() -> std::io::Result<()> {
             App::new()
                 .wrap(
                     DefaultHeaders::new()
-                        .add(DEFAULT_CONTENT_SECURITY_POLICY)
                         .add(DEFAULT_PERMISSIONS)
                         .add(DEFAULT_CONTENT_TYPE_OPTIONS)
                         .add(DEFAULT_FRAME_OPTIONS)
@@ -94,6 +91,7 @@ async fn main() -> std::io::Result<()> {
                 )
                 .wrap(middleware::Compress::default())
                 .wrap(middleware::NormalizePath::trim())
+                .wrap(from_fn(script_nonce::insert_script_nonce))
                 .app_data(db.clone())
                 .app_data(expiry_watch_sender.clone())
                 .app_data(config.clone())

src/script_nonce.rs

@@ -0,0 +1,35 @@
+use actix_web::{
+    body::MessageBody,
+    dev::{ServiceRequest, ServiceResponse},
+    http::header::{HeaderValue, CONTENT_SECURITY_POLICY},
+    Error, HttpMessage,
+};
+use actix_web_lab::middleware::Next;
+use rand::Rng;
+use std::fmt::Display;
+
+pub struct ScriptNonce(String);
+
+impl Display for ScriptNonce {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+pub async fn insert_script_nonce(
+    req: ServiceRequest,
+    next: Next<impl MessageBody>,
+) -> Result<ServiceResponse<impl MessageBody>, Error> {
+    let script_nonce = format!("{:02x}", rand::thread_rng().gen::<u128>());
+    req.extensions_mut()
+        .insert(ScriptNonce(script_nonce.clone()));
+    let mut res = next.call(req).await;
+    if let Ok(res) = res.as_mut() {
+        let value = format!("default-src 'none'; connect-src 'self'; img-src 'self'; media-src 'self'; font-src 'self'; script-src 'nonce-{script_nonce}'; style-src 'self'; object-src 'none'; base-uri 'self'; frame-src 'none'; frame-ancestors 'none'; form-action 'self'; require-trusted-types-for 'script';");
+        res.headers_mut().insert(
+            CONTENT_SECURITY_POLICY,
+            HeaderValue::from_str(&value).unwrap(),
+        );
+    }
+    res
+}

src/template.rs

@@ -1,11 +1,11 @@
 use std::{cmp, io::ErrorKind, str::FromStr};
 
-use actix_web::HttpRequest;
+use actix_web::{HttpMessage, HttpRequest};
 use time::Duration;
 use tokio::fs;
 use url::Url;
 
-use crate::config::Config;
+use crate::{config::Config, script_nonce::ScriptNonce};
 
 const INDEX_HTML: &str = include_str!("../template/index.html");
 const AUTH_HIDE_JS: &str = include_str!("../template/auth-hide.js");
@@ -34,7 +34,8 @@ pub fn build_uploaded_html(
     } else {
         UPLOAD_HTML.replace("{link}", &get_file_url(req, id, name))
     };
-    insert_abuse_template(upload_html, None, config)
+    let upload_html = insert_abuse_template(upload_html, None, config);
+    insert_script_nonce(req, upload_html)
 }
 
 pub fn get_file_url(req: &HttpRequest, id: &str, name: Option<&str>) -> String {
@@ -68,15 +69,11 @@ pub fn build_html_view_template(
             .replace("{file_name}", &name_snippet)
             .replace("{text}", &encoded_content)
     };
-    insert_abuse_template(html, Some(req), config)
+    let html = insert_abuse_template(html, Some(req), config);
+    insert_script_nonce(req, html)
 }
 
 pub async fn write_prefillable_templates(config: &Config) {
-    let index_path = config.static_dir.join("index.html");
-    fs::write(index_path, build_index_html(config))
-        .await
-        .expect("could not write index.html to static folder");
-
     let auth_hide_path = config.static_dir.join("auth-hide.js");
     if let Some(auth_hide_js) = build_auth_hide_js(config) {
         fs::write(auth_hide_path, auth_hide_js)
@@ -90,7 +87,7 @@ pub async fn write_prefillable_templates(config: &Config) {
     }
 }
 
-fn build_index_html(config: &Config) -> String {
+pub fn build_index_html(req: &HttpRequest, config: &Config) -> String {
     let mut html = INDEX_HTML.to_owned();
     if let Some(limit) = config.no_auth_limits.as_ref() {
         html = html
@@ -115,7 +112,7 @@ fn build_index_html(config: &Config) -> String {
     } else {
         html = html.replace("{max_size_snippet}", "");
     };
-    html
+    insert_script_nonce(req, html)
 }
 
 pub fn insert_abuse_template(html: String, req: Option<&HttpRequest>, config: &Config) -> String {
@@ -134,6 +131,12 @@ pub fn insert_abuse_template(html: String, req: Option<&HttpRequest>, config: &C
     }
 }
 
+pub fn insert_script_nonce(req: &HttpRequest, html: String) -> String {
+    let extensions = &req.extensions();
+    let script_nonce = extensions.get::<ScriptNonce>().expect("script_nonce available");
+    html.replace("{script_nonce}", &script_nonce.to_string())
+}
+
 fn render_file_size(size: u64) -> String {
     let magnitude = cmp::min((size as f64).log(1024.0) as u32, 5);
     let prefix = ["", "ki", "Mi", "Gi", "Ti", "Pi"][magnitude as usize];

src/upload.rs

@@ -3,7 +3,6 @@ use std::io::ErrorKind;
 use crate::config::Config;
 use crate::file_info::FileInfo;
 use crate::{file_info, multipart, template};
-use actix_files::NamedFile;
 use actix_multipart::Multipart;
 use actix_web::http::header::LOCATION;
 use actix_web::{error, web, Error, HttpRequest, HttpResponse};
@@ -18,12 +17,11 @@ const ID_CHARS: &[char] = &[
     'v', 'w', 'x', 'y', 'z', '1', '2', '3', '4', '5', '6', '7', '8', '9',
 ];
 
-pub async fn index(config: web::Data<Config>) -> Result<NamedFile, Error> {
-    let file = NamedFile::open(config.static_dir.join("index.html")).map_err(|file_err| {
-        log::error!("index.html could not be read {:?}", file_err);
-        error::ErrorInternalServerError("this file should be here but could not be found")
-    })?;
-    Ok(file.disable_content_disposition())
+pub async fn index(req: HttpRequest, config: web::Data<Config>) -> HttpResponse {
+    let index_html = template::build_index_html(&req, &config);
+    HttpResponse::Ok()
+        .content_type("text/html")
+        .body(index_html) 
 }
 
 pub async fn upload(

template/index.html

@@ -93,7 +93,7 @@
         repo
       </a>
     </footer>
-    <script src="/static/paste.js"></script>
-    <script src="/static/origin.js"></script>
+		<script nonce="{script_nonce}" src="/static/paste.js"></script>
+		<script nonce="{script_nonce}" src="/static/origin.js"></script>
   </body>
 </html>

template/text-view.html

@@ -36,6 +36,6 @@
         repo
       </a>
     </footer>
-    <script src="/static/copy.js"></script>
+    <script nonce="{script_nonce}" src="/static/copy.js"></script>
   </body>
 </html>

template/upload-short.html

@@ -36,6 +36,6 @@
         repo
       </a>
     </footer>
-    <script src="/static/copy.js"></script>
+    <script nonce="{script_nonce}" src="/static/copy.js"></script>
   </body>
 </html>

template/upload.html

@@ -32,6 +32,6 @@
         repo
       </a>
     </footer>
-    <script src="/static/copy.js"></script>
+    <script nonce="{script_nonce}" src="/static/copy.js"></script>
   </body>
 </html>

template/url-view.html

@@ -44,6 +44,6 @@
         repo
       </a>
     </footer>
-    <script src="/static/copy.js"></script>
+    <script nonce="{script_nonce}" src="/static/copy.js"></script>
   </body>
 </html>