Change CSP config format to be more intuitive

Author: literalplus

README.md

@@ -158,6 +158,7 @@ Environment variables (will overwrite other server configs)
 | HMD_HSTS_INCLUDE_SUBDOMAINS | `true` | set to include subdomains in HSTS (default is `true`) |
 | HMD_HSTS_MAX_AGE | `31536000` | max duration in seconds to tell clients to keep HSTS status (default is a year) |
 | HMD_HSTS_PRELOAD | `true` | whether to allow preloading of the site's HSTS status (e.g. into browsers) |
+| HMD_CSP_ENABLE | `true` | whether to enable Content Security Policy (directives cannot be configured with environment variables) |
 
 Application settings `config.json`
 ---
@@ -171,6 +172,7 @@ Application settings `config.json`
 | alloworigin | `['localhost']` | domain name whitelist |
 | usessl | `true` or `false` | set to use ssl server (if true will auto turn on `protocolusessl`) |
 | hsts | `{"enable": "true", "maxAgeSeconds": "31536000", "includeSubdomains": "true", "preload": "true"}` | [HSTS](https://en.wikipedia.org/wiki/HTTP_Strict_Transport_Security) options to use with HTTPS (default is the example value, max age is a year) |
+| csp | `{"enable": "true", "directives": {"scriptSrc": "trustwodthy-scripts.example.com"}, "upgradeInsecureRequests": "auto", "addDefaults": "true"}` | Configures [Content Security Policy](https://helmetjs.github.io/docs/csp/). Directives are directly passed to Helmet, so [their format](https://helmetjs.github.io/docs/csp/) applies. Further, some defaults are added so  that the application doesn't break. To disable adding these defaults, set `addDefaults` to `false`. If `usecdn` is on, default CDN locations are allowed too. By default (`auto`), insecure (HTTP) requests are upgraded to HTTPS via CSP if `usessl` is on. To change this behaviour, set `upgradeInsecureRequests` to either `true` or `false`. |
 | protocolusessl | `true` or `false` | set to use ssl protocol for resources path (only applied when domain is set) |
 | urladdport | `true` or `false` | set to add port on callback url (port 80 or 443 won't applied) (only applied when domain is set) |
 | usecdn | `true` or `false` | set to use CDN resources or not (default is `true`) |

app.js

@@ -125,7 +125,28 @@ function getCspWebSocketUrl (req, res) {
   return (req.protocol === 'http' ? 'ws:' : 'wss:') + config.serverurl.replace(/https?:/, "")
 }
 
+function mergeWithDefaults(configured, defaultDirective, cdnDirective) {
+  var directive = [].concat(configured)
+  if (config.csp.addDefaults && defaultDirective) {
+    directive = directive.concat(defaultDirective)
+  }
+  if (config.usecdn && cdnDirective) {
+    directive = directive.concat(cdnDirective)
+  }
+  return directive
+}
+
 if (config.csp.enable) {
+  var defaultDirectives = {
+    defaultSrc: ['\'self\''],
+    scriptSrc: ['\'self\'', 'vimeo.com', 'https://gist.github.com', 'www.slideshare.net', 'https://query.yahooapis.com', 'https://*.disqus.com', '\'unsafe-eval\''], // TODO: Remove unsafe-eval - webpack script-loader issues
+    imgSrc: ['*'],
+    styleSrc: ['\'self\'', '\'unsafe-inline\'', 'https://assets-cdn.github.com'], // unsafe-inline is required for some libs, plus used in views
+    fontSrc: ['\'self\'', 'https://public.slidesharecdn.com'],
+    objectSrc: ['*'], // Chrome PDF viewer treats PDFs as objects :/
+    childSrc: ['*'],
+    connectSrc: ['\'self\'', 'https://links.services.disqus.com', 'wss://realtime.services.disqus.com']
+  };
   var cdnDirectives = {
     scriptSrc: ['https://cdnjs.cloudflare.com', 'https://cdn.mathjax.org'],
     styleSrc: ['https://cdnjs.cloudflare.com', 'https://fonts.googleapis.com'],
@@ -134,11 +155,20 @@ if (config.csp.enable) {
   var directives = {}
   for (var propertyName in config.csp.directives) {
     if (config.csp.directives.hasOwnProperty(propertyName)) {
-      var directive = [].concat(config.csp.directives[propertyName])
-      if (config.usecdn && !!cdnDirectives[propertyName]) {
-        directive = directive.concat(cdnDirectives[propertyName])
-      }
-      directives[propertyName] = directive
+      directives[propertyName] = mergeWithDefaults(
+        config.csp.directives[propertyName],
+        defaultDirectives[propertyName],
+        cdnDirectives[propertyName]
+      )
+    }
+  }
+  for (var propertyName in defaultDirectives) {
+    if (!directives[propertyName]) {
+      directives[propertyName] = mergeWithDefaults(
+        [],
+        defaultDirectives[propertyName],
+        cdnDirectives[propertyName]
+      )
     }
   }
   directives.scriptSrc.push(getCspNonce)

config.json.example

@@ -22,6 +22,13 @@
             "includeSubdomains": "true",
             "preload": "true"
         },
+        csp: {
+	    "enable": "true",
+            "directives": {
+            },
+            "upgradeInsecureRequests": "auto"
+            "addDefaults": "true"
+        },
         "db": {
             "username": "",
             "password": "",

lib/config/default.js

@@ -15,17 +15,9 @@ module.exports = {
   },
   csp: {
     enable: true,
-    reportUri: '',
     directives: {
-      defaultSrc: ["'self'"],
-      scriptSrc: ["'self'", "'unsafe-eval'", "vimeo.com", "https://gist.github.com", "www.slideshare.net", "https://query.yahooapis.com", "https://*.disqus.com"],
-      imgSrc: ["*"],
-      styleSrc: ["'self'", "'unsafe-inline'", "https://assets-cdn.github.com"],
-      fontSrc: ["'self'", "https://public.slidesharecdn.com"],
-      objectSrc: ["*"],
-      childSrc: ["*"],
-      connectSrc: ["'self'", "https://links.services.disqus.com", "wss://realtime.services.disqus.com"]
     },
+    addDefaults: true,
     upgradeInsecureRequests: 'auto'
   },
   protocolusessl: false,

lib/config/environment.js

@@ -14,6 +14,9 @@ module.exports = {
     includeSubdomains: toBooleanConfig(process.env.HMD_HSTS_INCLUDE_SUBDOMAINS),
     preload: toBooleanConfig(process.env.HMD_HSTS_PRELOAD)
   },
+  csp: {
+    enable: toBooleanConfig(process.env.HMD_CSP_ENABLE)
+  },
   protocolusessl: toBooleanConfig(process.env.HMD_PROTOCOL_USESSL),
   alloworigin: process.env.HMD_ALLOW_ORIGIN ? process.env.HMD_ALLOW_ORIGIN.split(',') : undefined,
   usecdn: toBooleanConfig(process.env.HMD_USECDN),