add Content Security Policy (#1252)

* add Content Security Policy

* remove reflect-metadata on production builds to get rid of unsafe-eval

* fix baseCSP usage

* add SRI to CSP

* add blob: to media-src

* remove SRI

* CSP set to reportOnly

* adding data: to connect-src CSP

* remove block-all-mixed-content

* add report-uri support

3 files changed, 48 insertions, 1 deletions

diff --git a/server/middlewares/csp.ts b/server/middlewares/csp.ts
new file mode 100644
index 000000000..a0ed3710b
--- /dev/null
+++ b/server/middlewares/csp.ts
@@ -0,0 +1,45 @@
+import * as helmet from 'helmet'
+import { CONFIG } from '../initializers/constants'
+
+const baseDirectives = Object.assign({},
+  {
+    defaultSrc: ["'none'"], // by default, not specifying default-src = '*'
+    connectSrc: ['*', 'data:'],
+    mediaSrc: ["'self'", 'https:', 'blob:'],
+    fontSrc: ["'self'", 'data:'],
+    imgSrc: ["'self'", 'data:'],
+    scriptSrc: ["'self' 'unsafe-inline'"],
+    styleSrc: ["'self' 'unsafe-inline'"],
+    // objectSrc: ["'none'"], // only define to allow plugins, else let defaultSrc 'none' block it
+    formAction: ["'self'"],
+    frameAncestors: ["'none'"],
+    baseUri: ["'self'"],
+    pluginTypes: ["'none'"],
+    manifestSrc: ["'self'"],
+    frameSrc: ["'self'"], // instead of deprecated child-src / self because of test-embed
+    workerSrc: ["'self'"], // instead of deprecated child-src
+    upgradeInsecureRequests: true
+  },
+  (CONFIG.SERVICES['CSP-LOGGER'] != null) ? { reportUri: CONFIG.SERVICES['CSP-LOGGER'] } : {}
+)
+
+const baseCSP = helmet.contentSecurityPolicy({
+  directives: baseDirectives,
+  browserSniff: false,
+  reportOnly: true
+})
+
+const embedCSP = helmet.contentSecurityPolicy({
+  directives: Object.assign(baseDirectives, {
+    frameAncestors: ['*']
+  }),
+  browserSniff: false, // assumes a modern browser, but allows CDN in front
+  reportOnly: true
+})
+
+// ---------------------------------------------------------------------------
+
+export {
+  baseCSP,
+  embedCSP
+}
diff --git a/server/middlewares/dnt.ts b/server/middlewares/dnt.ts
index cabad39c6..607def855 100644
--- a/server/middlewares/dnt.ts
+++ b/server/middlewares/dnt.ts
@@ -10,4 +10,4 @@ const advertiseDoNotTrack = (_, res, next) => {
 
 export {
   advertiseDoNotTrack
- }
+}
diff --git a/server/middlewares/index.ts b/server/middlewares/index.ts
index 0cef26953..b758a8586 100644
--- a/server/middlewares/index.ts
+++ b/server/middlewares/index.ts
@@ -6,3 +6,5 @@ export * from './pagination'
 export * from './servers'
 export * from './sort'
 export * from './user-right'
+export * from './dnt'
+export * from './csp'