98 lines
3.1 KiB
JavaScript
98 lines
3.1 KiB
JavaScript
const config = require('./config')
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const { v4: uuidv4 } = require('uuid')
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const CspStrategy = {}
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const defaultDirectives = {
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defaultSrc: ['\'self\''],
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scriptSrc: ['\'self\'', 'vimeo.com', 'https://gist.github.com', 'www.slideshare.net'],
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imgSrc: ['*'],
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styleSrc: ['\'self\'', '\'unsafe-inline\'', 'https://github.githubassets.com'], // unsafe-inline is required for some libs, plus used in views
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fontSrc: ['\'self\'', 'data:', 'https://public.slidesharecdn.com'],
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objectSrc: ['*'], // Chrome PDF viewer treats PDFs as objects :/
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mediaSrc: ['*'],
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childSrc: ['*'],
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connectSrc: ['*']
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}
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const disqusDirectives = {
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scriptSrc: ['https://disqus.com', 'https://*.disqus.com', 'https://*.disquscdn.com'],
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styleSrc: ['https://*.disquscdn.com'],
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fontSrc: ['https://*.disquscdn.com']
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}
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const googleAnalyticsDirectives = {
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scriptSrc: ['https://www.google-analytics.com']
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}
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const dropboxDirectives = {
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scriptSrc: ['https://www.dropbox.com', '\'unsafe-inline\'']
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}
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CspStrategy.computeDirectives = function () {
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const directives = {}
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mergeDirectives(directives, config.csp.directives)
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mergeDirectivesIf(config.csp.addDefaults, directives, defaultDirectives)
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mergeDirectivesIf(config.csp.addDisqus, directives, disqusDirectives)
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mergeDirectivesIf(config.csp.addGoogleAnalytics, directives, googleAnalyticsDirectives)
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mergeDirectivesIf(config.dropbox.appKey, directives, dropboxDirectives)
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if (!areAllInlineScriptsAllowed(directives)) {
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addInlineScriptExceptions(directives)
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}
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addUpgradeUnsafeRequestsOptionTo(directives)
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addReportURI(directives)
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return directives
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}
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function mergeDirectives (existingDirectives, newDirectives) {
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for (const propertyName in newDirectives) {
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const newDirective = newDirectives[propertyName]
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if (newDirective) {
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const existingDirective = existingDirectives[propertyName] || []
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existingDirectives[propertyName] = existingDirective.concat(newDirective)
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}
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}
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}
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function mergeDirectivesIf (condition, existingDirectives, newDirectives) {
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if (condition) {
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mergeDirectives(existingDirectives, newDirectives)
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}
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}
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function areAllInlineScriptsAllowed (directives) {
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return directives.scriptSrc.indexOf('\'unsafe-inline\'') !== -1
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}
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function addInlineScriptExceptions (directives) {
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directives.scriptSrc.push(getCspNonce)
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// TODO: This is the SHA-256 hash of the inline script in build/reveal.js/plugins/notes/notes.html
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// Any more clean solution appreciated.
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directives.scriptSrc.push('\'sha256-81acLZNZISnyGYZrSuoYhpzwDTTxi7vC1YM4uNxqWaM=\'')
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}
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function getCspNonce (req, res) {
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return "'nonce-" + res.locals.nonce + "'"
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}
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function addUpgradeUnsafeRequestsOptionTo (directives) {
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if (config.csp.upgradeInsecureRequests === 'auto' && config.useSSL) {
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directives.upgradeInsecureRequests = []
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} else if (config.csp.upgradeInsecureRequests === true) {
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directives.upgradeInsecureRequests = []
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}
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}
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function addReportURI (directives) {
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if (config.csp.reportURI) {
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directives.reportUri = config.csp.reportURI
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}
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}
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CspStrategy.addNonceToLocals = function (req, res, next) {
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res.locals.nonce = uuidv4()
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next()
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}
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module.exports = CspStrategy
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