feat: Add ALLOWED_IFRAME_ORIGINS configuration and update security headers (#47) (#48)

- Introduced ALLOWED_IFRAME_ORIGINS environment variable to specify trusted origins for iframe embedding.
- Updated security headers middleware to conditionally allow specified origins in Content Security Policy.
- Enhanced documentation in README.md to explain the new configuration and its security implications.

Fixes #35

README.md

@@ -123,6 +123,19 @@ docker run -p 3000:3000 -v "${PWD}\local_uploads:/app/uploads" dumbwareio/dumbdr
 | APPRISE_SIZE_UNIT| Size unit for notifications           | Auto    | No       |
 | AUTO_UPLOAD      | Enable automatic upload on file selection | false   | No       |
 | ALLOWED_EXTENSIONS| Comma-separated list of allowed file extensions | None    | No       |
+| ALLOWED_IFRAME_ORIGINS | Comma-separated list of origins allowed to embed the app in an iframe (e.g. https://organizr.example.com,https://myportal.com) | None | No |
+
+### ALLOWED_IFRAME_ORIGINS
+
+To allow this app to be embedded in an iframe on specific origins (such as Organizr), set the `ALLOWED_IFRAME_ORIGINS` environment variable to a comma-separated list of allowed parent origins. Example:
+
+```env
+ALLOWED_IFRAME_ORIGINS=https://organizr.example.com,https://myportal.com
+```
+
+- If not set, the app will only allow itself to be embedded in an iframe on the same origin (default security).
+- If set, the app will allow embedding in iframes on the specified origins and itself.
+- **Security Note:** Only add trusted origins. Allowing arbitrary origins can expose your app to clickjacking and other attacks.
 
 ### File Extension Filtering
 To restrict which file types can be uploaded, set the `ALLOWED_EXTENSIONS` environment variable. For example:

src/config/index.js

@@ -66,7 +66,13 @@ const config = {
   // File extensions
   allowedExtensions: process.env.ALLOWED_EXTENSIONS ? 
     process.env.ALLOWED_EXTENSIONS.split(',').map(ext => ext.trim().toLowerCase()) : 
-    null
+    null,
+
+  // Allowed iframe origins (for embedding in iframes)
+  // Comma-separated list of origins, e.g. "https://organizr.example.com,https://dumb.myportal.com"
+  allowedIframeOrigins: process.env.ALLOWED_IFRAME_ORIGINS
+    ? process.env.ALLOWED_IFRAME_ORIGINS.split(',').map(origin => origin.trim()).filter(Boolean)
+    : null
 };
 
 // Validate required settings

src/middleware/security.js

@@ -6,27 +6,32 @@
 
 const { safeCompare } = require('../utils/security');
 const logger = require('../utils/logger');
+const { config } = require('../config');
 
 /**
  * Security headers middleware
  */
 function securityHeaders(req, res, next) {
   // Content Security Policy
-  res.setHeader(
-    'Content-Security-Policy',
+  let csp =
     "default-src 'self'; " +
     "style-src 'self' 'unsafe-inline' cdn.jsdelivr.net; " +
     "script-src 'self' 'unsafe-inline' cdn.jsdelivr.net; " +
-    "img-src 'self' data: blob:;"
-  );
+    "img-src 'self' data: blob:;";
 
-  // X-Content-Type-Options
-  res.setHeader('X-Content-Type-Options', 'nosniff');
-  
-  // X-Frame-Options
+  // If allowedIframeOrigins is set, allow those origins to embed via iframe
+  if (config.allowedIframeOrigins && config.allowedIframeOrigins.length > 0) {
+    // Remove X-Frame-Options header (do not set it)
+    // Add frame-ancestors directive to CSP
+    const frameAncestors = ["'self'", ...config.allowedIframeOrigins].join(' ');
+    csp += ` frame-ancestors ${frameAncestors};`;
+  } else {
+    // Default: only allow same origin if not configured
     res.setHeader('X-Frame-Options', 'SAMEORIGIN');
+  }
 
-  // X-XSS-Protection
+  res.setHeader('Content-Security-Policy', csp);
+  res.setHeader('X-Content-Type-Options', 'nosniff');
   res.setHeader('X-XSS-Protection', '1; mode=block');
 
   // Strict Transport Security (when in production)