feat(csp): SRI hashes for SSG mode

src/runtime/nitro/plugins/02-cspSsg.ts

@@ -23,8 +23,8 @@ export default defineNitroPlugin((nitroApp) => {
       return
     }
 
-    const scriptHashes: string[] = []
-    const styleHashes: string[] = []
+    const scriptHashes: Set<string> = new Set()
+    const styleHashes: Set<string> = new Set()
     const hashAlgorithm = 'sha256'
 
     // Scan all relevant sections of the NuxtRenderHtmlContext
@@ -42,10 +42,10 @@ export default defineNitroPlugin((nitroApp) => {
           const integrity = scriptAttrs?.integrity
           if (!src && scriptText) {
             // Hash inline scripts with content
-            scriptHashes.push(generateHash(scriptText, hashAlgorithm))
+            scriptHashes.add(generateHash(scriptText, hashAlgorithm))
           } else if (src && integrity) {
             // Whitelist external scripts with integrity
-            scriptHashes.push(`'${integrity}'`)
+            scriptHashes.add(`'${integrity}'`)
           }
         })
 
@@ -54,7 +54,41 @@ export default defineNitroPlugin((nitroApp) => {
           const styleText = $(style).text()
           if (styleText) {
             // Hash inline styles with content
-            styleHashes.push(generateHash(styleText, hashAlgorithm))
+            styleHashes.add(generateHash(styleText, hashAlgorithm))
+          }
+        })
+
+        // Parse all link tags
+        $('link').each((i, link) => {
+          const linkAttrs = $(link).attr()
+          const integrity = linkAttrs?.integrity
+          // Whitelist links to external resources with integrity
+          if (integrity) {
+            const rel = linkAttrs?.rel
+            // HTML standard defines only 3 rel values for valid integrity attributes on links : stylesheet, preload and modulepreload
+            // https://html.spec.whatwg.org/multipage/semantics.html#attr-link-integrity
+            if (rel === 'stylesheet') {
+              // style: add to style-src
+              styleHashes.add(`'${integrity}'`)
+            } else if (rel === 'preload') {
+              // Fetch standard defines the destination (https://fetch.spec.whatwg.org/#destination-table)
+              // This table is the official mapping between HTML and CSP
+              // We only support script-src for now, but we could populate other policies in the future
+              const as = linkAttrs.as
+              switch (as) {
+                case 'script':
+                case 'audioworklet':
+                case 'paintworklet':
+                case 'xlst':
+                  scriptHashes.add(`'${integrity}'`)
+                  break
+                default:
+                  break
+              }
+            } else if (rel === 'modulepreload') {
+              // script is the default and only possible destination
+              scriptHashes.add(`'${integrity}'`)
+            }
           }
         })
       }
@@ -73,21 +107,22 @@ export default defineNitroPlugin((nitroApp) => {
   })
 
   // Insert hashes in the CSP meta tag for both the script-src and the style-src policies
-  function generateCspMetaTag (policies: ContentSecurityPolicyValue, scriptHashes: string[], styleHashes: string[]) {
+  function generateCspMetaTag (policies: ContentSecurityPolicyValue, scriptHashes: Set<string>, styleHashes: Set<string>) {
     const unsupportedPolicies:Record<string, boolean> = {
       'frame-ancestors': true,
       'report-uri': true,
       sandbox: true
     }
 
     const tagPolicies = defu(policies) as ContentSecurityPolicyValue
-    if (scriptHashes.length > 0 && moduleOptions.ssg?.hashScripts) {
+    if (scriptHashes.size > 0 && moduleOptions.ssg?.hashScripts) {
       // Remove '""'
-      tagPolicies['script-src'] = (tagPolicies['script-src'] ?? []).concat(scriptHashes)
+      tagPolicies['script-src'] = (tagPolicies['script-src'] ?? []).concat(...scriptHashes)
     }
-    if (styleHashes.length > 0 && moduleOptions.ssg?.hashStyles) {
+
+    if (styleHashes.size > 0 && moduleOptions.ssg?.hashStyles) {
       // Remove '""'
-      tagPolicies['style-src'] = (tagPolicies['style-src'] ?? []).concat(styleHashes)
+      tagPolicies['style-src'] = (tagPolicies['style-src'] ?? []).concat(...styleHashes)
     }
 
     const contentArray: string[] = []

test/fixtures/ssg/.nuxtrc

@@ -0,0 +1 @@
+imports.autoImport=true

test/fixtures/ssg/nuxt.config.ts

@@ -0,0 +1,42 @@
+import { defineNuxtConfig } from 'nuxt/config'
+
+export default defineNuxtConfig({
+
+  modules: ['../../../src/module'],
+
+  // Per route configuration
+  routeRules: {
+    '/': {
+      prerender: true
+    },
+    '/inline-script': {
+      prerender: true,
+    },
+    '/inline-style': {
+      prerender: true
+    },
+    '/external-script': {
+      prerender: true
+    },
+    '/external-style': {
+      prerender: true
+    },
+    '/external-link': {
+      prerender: true
+    },
+    '/not-ssg': {
+      prerender: false
+    }
+  },
+
+  // Global configuration
+  security: {
+    rateLimiter: false,
+    sri: true,
+    ssg: {
+      hashScripts: true,
+      hashStyles: true
+    }
+  },
+
+})

test/fixtures/ssg/package.json

@@ -0,0 +1,5 @@
+{
+  "private": true,
+  "name": "basic",
+  "type": "module"
+}

test/fixtures/ssg/pages/external-link.vue

@@ -0,0 +1,12 @@
+<template>
+  <div>
+    Default page
+  </div>
+</template>
+<script setup>
+useHead({
+  link: [
+    { rel: 'icon', href: '/icon.png' }
+  ]
+})
+</script>

test/fixtures/ssg/pages/external-script.vue

@@ -0,0 +1,12 @@
+<template>
+  <div>
+    Default page
+  </div>
+</template>
+<script setup>
+useHead({
+  script: [
+    { src: '/external.js' }
+  ]
+})
+</script>

test/fixtures/ssg/pages/external-style.vue

@@ -0,0 +1,12 @@
+<template>
+  <div>
+    Default page
+  </div>
+</template>
+<script setup>
+useHead({
+  link: [
+    { rel: 'stylesheet', href: '/external.css' }
+  ]
+})
+</script>

test/fixtures/ssg/pages/index.vue

@@ -0,0 +1,5 @@
+<template>
+  <div>
+    Default page
+  </div>
+</template>

test/fixtures/ssg/pages/inline-script.vue

@@ -0,0 +1,12 @@
+<template>
+  <div>
+    Default page
+  </div>
+</template>
+<script setup>
+useHead({
+  script: [
+    { textContent: 'window.myImportantVar = 1', type: 'text/javascript' }
+  ]
+})
+</script>

test/fixtures/ssg/pages/inline-style.vue

@@ -0,0 +1,12 @@
+<template>
+  <div>
+    Default page
+  </div>
+</template>
+<script setup>
+useHead({
+  style: [
+    { textContent: 'div { color: blue }', type: 'text/css' }
+  ]
+})
+</script>

test/fixtures/ssg/pages/not-ssg.vue

@@ -0,0 +1,17 @@
+<template>
+  <div>
+    Default page
+  </div>
+</template>
+<script setup>
+useHead({
+  script: [
+    { src: '/external.js' },
+    { textContent: 'window.myImportantVar = 4', type: 'text/javascript' }
+  ],
+  link: [
+    { rel: 'stylesheet', href: '/external.css' },
+    { rel: 'icon', href: '/icon.png' }
+  ]
+})
+</script>

test/fixtures/ssg/public/external.css

@@ -0,0 +1,3 @@
+div {
+  color: red;
+}

test/fixtures/ssg/public/external.js

@@ -0,0 +1 @@
+console.log('Hello World')