Reverting usage of RE2 (WIP):
**Breaking changes** The livechat v13 introduced a new library to handle regular expressions in forbidden words, to avoid [ReDOS](https://en.wikipedia.org/wiki/ReDoS) attacks. Unfortunately, this library was not able to install itself properly on some systems, and some admins were not able to install the livechat plugin. That's why we have disabled this library in v14, and introduce a new settings to enable regexp in forbidden words. By default this settings is disabled, and your users won't be able to use regexp in their forbidden words. The risk by enabling this feature is that a malicious user could cause a denial of service for the chat bot, by using a special crafted regular expression in their channel options, and sending a special crafter message in one of their rooms. If you trust your users (those who have rights to livestream), you can enable the settings. Otherwise it is not recommanded. See the documentation for more informations. **Minor changes and fixes** * Channel's forbidden words: new "enable" column. * New settings to enable regular expressions for channel forbidden words. * "Channel advanced configuration" settings: removing the "experimental feature" label.
This commit is contained in:
John Livingston
@ -11,9 +11,6 @@ import {
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noDuplicateDefaultDelay,
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noDuplicateMaxDelay
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} from '../../../../shared/lib/constants'
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import * as RE2 from 're2'
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type SanitizeMode = 'validation' | 'read'
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/**
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* Sanitize data so that they can safely be used/stored for channel configuration configuration.
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@ -25,10 +22,9 @@ type SanitizeMode = 'validation' | 'read'
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* @param mode Sanitization mode. 'validation': when verifiying user input. 'read': when reading from disk.
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*/
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async function sanitizeChannelConfigurationOptions (
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_options: RegisterServerOptions,
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options: RegisterServerOptions,
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_channelId: number | string,
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data: unknown,
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mode: SanitizeMode
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data: unknown
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): Promise<ChannelConfigurationOptions> {
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if (!_assertObjectType(data)) {
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throw new Error('Invalid data type')
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@ -96,7 +92,7 @@ async function sanitizeChannelConfigurationOptions (
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bot: {
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enabled: _readBoolean(botData, 'enabled'),
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nickname: _readSimpleInput(botData, 'nickname', true),
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forbiddenWords: await _readForbiddenWords(botData, mode),
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forbiddenWords: await _readForbiddenWords(options, botData),
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forbidSpecialChars: await _readForbidSpecialChars(botData),
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noDuplicate: await _readNoDuplicate(botData),
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quotes: _readQuotes(botData),
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@ -206,7 +202,7 @@ function _readMultiLineString (data: Record<string, unknown>, f: string): string
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return s
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}
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async function _readRegExpArray (data: Record<string, unknown>, f: string, mode: SanitizeMode): Promise<string[]> {
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async function _readRegExpArray (data: Record<string, unknown>, f: string): Promise<string[]> {
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// Note: this function can instanciate a lot of RegExp.
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// To avoid freezing the server, we make it async, and will validate each regexp in a separate tick.
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if (!(f in data)) {
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@ -224,24 +220,11 @@ async function _readRegExpArray (data: Record<string, unknown>, f: string, mode:
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// ignore empty values
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continue
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}
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// value must be a valid RE2 regexp
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// value must be a valid regexp
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try {
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async function _validate (v: string): Promise<void> {
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// Before livechat v13, the bot was using RegExp.
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// Now it is using RE2, to avoid ReDOS attacks.
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// RE2 does not accept all regular expressions.
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// So, here come the question about settings saved before...
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// So we introduce the "mode" parameter.
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// When reading from disk, we want to be more permissive.
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// When validating frontend data, we want to be more restrictive.
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// Note: the bot will simply ignore any invalid RE2 expression, and generate an error log on loading.
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if (mode === 'read') {
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// eslint-disable-next-line no-new
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new RegExp(v)
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} else {
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// eslint-disable-next-line no-new, new-cap
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new RE2.default(v)
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}
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// eslint-disable-next-line no-new
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new RegExp(v)
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}
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await _validate(v)
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} catch (err: any) {
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@ -253,9 +236,11 @@ async function _readRegExpArray (data: Record<string, unknown>, f: string, mode:
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}
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async function _readForbiddenWords (
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botData: Record<string, unknown>,
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mode: SanitizeMode
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options: RegisterServerOptions,
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botData: Record<string, unknown>
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): Promise<ChannelConfigurationOptions['bot']['forbiddenWords']> {
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const enableUsersRegexp = (await options.settingsManager.getSetting('enable-users-regexp')) === true
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if (!Array.isArray(botData.forbiddenWords)) {
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throw new Error('Invalid forbiddenWords data')
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}
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@ -265,9 +250,10 @@ async function _readForbiddenWords (
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throw new Error('Invalid entry in botData.forbiddenWords')
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}
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const regexp = !!fw.regexp
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let entries
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if (regexp) {
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entries = await _readRegExpArray(fw, 'entries', mode)
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entries = await _readRegExpArray(fw, 'entries')
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} else {
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entries = _readStringArray(fw, 'entries')
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}
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@ -276,7 +262,17 @@ async function _readForbiddenWords (
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const reason = fw.reason ? _readSimpleInput(fw, 'reason') : undefined
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const comments = fw.comments ? _readMultiLineString(fw, 'comments') : undefined
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// Enabled was introduced in v14. So we must set to true if not present.
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let enabled = !('enabled' in fw) ? true : _readBoolean(fw, 'enabled')
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if (enabled && regexp && !enableUsersRegexp) {
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// here we don't fail, we just change the value.
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// This is usefull when the settings changes:
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// RoomChannel.singleton().rebuildData() will automatically update data.
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enabled = false
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}
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result.push({
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enabled,
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regexp,
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entries,
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applyToModerators,
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@ -38,7 +38,7 @@ async function getChannelConfigurationOptions (
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const content = await fs.promises.readFile(filePath, {
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encoding: 'utf-8'
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})
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const sanitized = await sanitizeChannelConfigurationOptions(options, channelId, JSON.parse(content), 'read')
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const sanitized = await sanitizeChannelConfigurationOptions(options, channelId, JSON.parse(content))
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return sanitized
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}
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@ -188,7 +188,7 @@ function _getForbiddenWordsHandler (
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return handler
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}
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handler.enabled = true
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handler.enabled = forbiddenWords.enabled
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const rule: any = {
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name: id
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}
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@ -262,7 +262,6 @@ function _getForbidSpecialCharsHandler (
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name: id,
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regexp,
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modifiers: 'us',
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regexp_engine: 'regexp', // FIXME: node-re2 is not compatible with \p{Emoji} and co, so we ensure to use RegExp here
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reason: forbidSpecialChars.reason
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}
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handler.options.rules.push(rule)
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