feat: add organizations whitelist to GitHub OAuth

Currently CodiMD does not support limiting access of GitHub OAuth users
based on their organization membership. This is a very useful
functionality for teams that want to limit write access to their notes.

I've implemented a crude solution to this problem, which most probably
requires some adjusments to make it better. I'm not sure if this
implementation is kosher, but it definitely works on my deployment.

Open to suggestions on how I can improve it.

Signed-off-by: Jakub Sokołowski <jakub@status.im>

app.json

@@ -80,6 +80,14 @@
             "description": "GitHub API client secret",
             "required": false
         },
+        "CMD_GITHUB_ORGANIZATIONS": {
+            "description": "GitHub whitelist of orgs",
+            "required": false
+        },
+        "CMD_GITHUB_SCOPES": {
+            "description": "GitHub OAuth API scopes",
+            "required": false
+        },
         "CMD_BITBUCKET_CLIENTID": {
             "description": "Bitbucket API client id",
             "required": false

config.json.example

@@ -54,6 +54,8 @@
         "github": {
             "clientID": "change this",
             "clientSecret": "change this"
+            "organizations": ["names of github organizations allowed, optional"],
+            "scopes": ["defaults to 'read:user' scope for auth user"],
         },
         "gitlab": {
             "baseURL": "change this",

lib/auth/github/index.js

@@ -1,12 +1,17 @@
 'use strict'
 
 const Router = require('express').Router
+const request = require('request')
 const passport = require('passport')
 const GithubStrategy = require('passport-github').Strategy
+const { InternalOAuthError } = require('passport-oauth2')
 const config = require('../../config')
 const response = require('../../response')
 const { setReturnToFromReferer, passportGeneralCallback } = require('../utils')
 const { URL } = require('url')
+const { promisify } = require('util')
+
+const rp = promisify(request)
 
 const githubAuth = module.exports = Router()
 
@@ -15,20 +20,47 @@ function githubUrl (path) {
 }
 
 passport.use(new GithubStrategy({
+  scope: (config.github.organizations ?
+    config.github.scopes.concat(['read:org']) : config.github.scope),
   clientID: config.github.clientID,
   clientSecret: config.github.clientSecret,
   callbackURL: config.serverURL + '/auth/github/callback',
   authorizationURL: githubUrl('login/oauth/authorize'),
   tokenURL: githubUrl('login/oauth/access_token'),
   userProfileURL: githubUrl('api/v3/user')
-}, passportGeneralCallback))
+}, async (accessToken, refreshToken, profile, done) => {
+  if (!config.github.organizations) {
+    return passportGeneralCallback(accessToken, refreshToken, profile, done)
+  }
+  const { statusCode, body: data } = await rp({
+    url: `https://api.github.com/user/orgs`,
+    method: 'GET', json: true, timeout: 2000,
+    headers: {
+      'Authorization': `token ${accessToken}`,
+      'User-Agent': 'nodejs-http'
+    }
+  })
+  if (statusCode != 200) {
+    return done(InternalOAuthError(
+      `Failed to query organizations for user: ${profile.username}`
+    ))
+  }
+  const orgs = data.map(({login}) => login)
+  for (const org of orgs) {
+    if (config.github.organizations.includes(org)) {
+      return passportGeneralCallback(accessToken, refreshToken, profile, done)
+    }
+  }
+  return done(InternalOAuthError(
+    `User orgs not whitelisted: ${profile.username} (${orgs.join(',')})`
+  ))
+}))
 
 githubAuth.get('/auth/github', function (req, res, next) {
   setReturnToFromReferer(req)
   passport.authenticate('github')(req, res, next)
 })
 
-// github auth callback
 githubAuth.get('/auth/github/callback',
   passport.authenticate('github', {
     successReturnToOrRedirect: config.serverURL + '/',

lib/config/default.js

@@ -115,7 +115,9 @@ module.exports = {
   github: {
     enterpriseURL: undefined, // if you use github.com, not need to specify
     clientID: undefined,
-    clientSecret: undefined
+    clientSecret: undefined,
+    organizations: [],
+    scopes: ['read:user']
   },
   gitlab: {
     baseURL: undefined,

lib/config/environment.js

@@ -69,7 +69,9 @@ module.exports = {
   github: {
     enterpriseURL: process.env.CMD_GITHUB_ENTERPRISE_URL,
     clientID: process.env.CMD_GITHUB_CLIENTID,
-    clientSecret: process.env.CMD_GITHUB_CLIENTSECRET
+    clientSecret: process.env.CMD_GITHUB_CLIENTSECRET,
+    organizations: toArrayConfig(process.env.CMD_GITHUB_ORGANIZATIONS),
+    scopes: toArrayConfig(process.env.CMD_GITHUB_SCOPES),
   },
   bitbucket: {
     clientID: process.env.CMD_BITBUCKET_CLIENTID,

scalingo.json

@@ -80,6 +80,14 @@
             "description": "GitHub API client secret",
             "required": false
         },
+        "CMD_GITHUB_ORGANIZATIONS": {
+            "description": "GitHub whitelist of orgs",
+            "required": false
+        },
+        "CMD_GITHUB_SCOPES": {
+            "description": "GitHub OAuth API scopes",
+            "required": false
+        },
         "CMD_BITBUCKET_CLIENTID": {
             "description": "Bitbucket API client id",
             "required": false