Merge pull request #35899 from overleaf/bg-custom-multer-workaround

add custom multer upload handler to prevent leaked files

GitOrigin-RevId: 7b390d326b4cf81fd82c532c53e9772cb4107a29

services/web/app/src/Features/Uploads/ProjectUploadController.mjs

@@ -10,8 +10,6 @@ import EditorController from '../Editor/EditorController.mjs'
 import ProjectLocator from '../Project/ProjectLocator.mjs'
 import Settings from '@overleaf/settings'
 import { InvalidZipFileError } from './ArchiveErrors.mjs'
-import multer from 'multer'
-import lodash from 'lodash'
 import { expressify } from '@overleaf/promise-utils'
 import {
   DuplicateNameError,
@@ -22,10 +20,9 @@ import {
 import DocumentConversionManager from './DocumentConversionManager.mjs'
 import ProjectOptionsHandler from '../Project/ProjectOptionsHandler.mjs'
 import AnalyticsManager from '../Analytics/AnalyticsManager.mjs'
+import { multer, multerUploadHandler } from '../../infrastructure/Multer.mjs'
 import { parseReq, z, zz } from '../../infrastructure/Validation.mjs'
 
-const defaultsDeep = lodash.defaultsDeep
-
 const uploadMetaTypeSchema = z.string().optional()
 
 const uploadProjectSchema = z.object({
@@ -72,17 +69,12 @@ const importDocumentSchema = z.object({
   file: zz.uploadedFile(),
 })
 
-const upload = multer(
-  defaultsDeep(
-    {
-      dest: Settings.path.uploadFolder,
-      limits: {
-        fileSize: Settings.maxUploadSize,
-      },
-    },
-    Settings.multerOptions
-  )
-)
+const upload = multerUploadHandler({
+  dest: Settings.path.uploadFolder,
+  limits: {
+    fileSize: Settings.maxUploadSize,
+  },
+})
 
 /**
  * @param {any} req

services/web/app/src/Features/Uploads/UploadsRouter.mjs

@@ -5,6 +5,7 @@ import { RateLimiter } from '../../infrastructure/RateLimiter.mjs'
 import RateLimiterMiddleware from '../Security/RateLimiterMiddleware.mjs'
 import Settings from '@overleaf/settings'
 import AsyncLocalStorage from '../../infrastructure/AsyncLocalStorage.mjs'
+import { multerErrorHandler } from '../../infrastructure/Multer.mjs'
 import { getRawReqInput } from '../../infrastructure/Validation.mjs'
 
 const rateLimiters = {
@@ -25,7 +26,8 @@ export default {
       AuthenticationController.requireLogin(),
       RateLimiterMiddleware.rateLimit(rateLimiters.projectUpload),
       ProjectUploadController.multerMiddleware,
-      ProjectUploadController.uploadProject
+      ProjectUploadController.uploadProject,
+      multerErrorHandler
     )
 
     if (Settings.enablePandocConversions) {
@@ -34,7 +36,8 @@ export default {
         AuthenticationController.requireLogin(),
         RateLimiterMiddleware.rateLimit(rateLimiters.projectUpload),
         ProjectUploadController.multerMiddleware,
-        ProjectUploadController.importDocument
+        ProjectUploadController.importDocument,
+        multerErrorHandler
       )
       // Keep old route for backwards compatibility with old frontends that haven't reloaded
       webRouter.post(
@@ -46,7 +49,8 @@ export default {
           getRawReqInput(req).query.type = 'docx'
           next()
         },
-        ProjectUploadController.importDocument
+        ProjectUploadController.importDocument,
+        multerErrorHandler
       )
     }
 
@@ -64,7 +68,8 @@ export default {
         AsyncLocalStorage.middleware,
         AuthorizationMiddleware.ensureUserCanWriteProjectContent,
         ProjectUploadController.multerMiddleware,
-        ProjectUploadController.uploadFile
+        ProjectUploadController.uploadFile,
+        multerErrorHandler
       )
     } else {
       webRouter.post(
@@ -74,7 +79,8 @@ export default {
         AsyncLocalStorage.middleware,
         AuthorizationMiddleware.ensureUserCanWriteProjectContent,
         ProjectUploadController.multerMiddleware,
-        ProjectUploadController.uploadFile
+        ProjectUploadController.uploadFile,
+        multerErrorHandler
       )
     }
   },

services/web/app/src/infrastructure/Multer.mjs

@@ -0,0 +1,66 @@
+import fs from 'node:fs'
+import Path from 'node:path'
+import crypto from 'node:crypto'
+import multer from 'multer'
+import lodash from 'lodash'
+import Settings from '@overleaf/settings'
+import logger from '@overleaf/logger'
+
+const defaultsDeep = lodash.defaultsDeep
+
+export { multer }
+
+/* multer upload handler with automatic cleanup to work around
+ * https://github.com/expressjs/multer/issues/259
+ */
+
+function filenameWithCleanup(uploadDir) {
+  return function (req, file, cb) {
+    const name = crypto.randomUUID()
+    // add an event handler to clean up files on aborted requests
+    req.once('close', () => {
+      if (!req.complete) {
+        const uploadPath = Path.join(uploadDir, name)
+        fs.unlink(uploadPath, err => {
+          if (err && err.code !== 'ENOENT') {
+            logger.warn(
+              { err, uploadPath },
+              'error deleting uploaded file on multer cleanup'
+            )
+          }
+        })
+      }
+    })
+    cb(null, name)
+  }
+}
+
+export function multerUploadHandler(options = {}) {
+  const mergedOptions = defaultsDeep({}, options, Settings.multerOptions)
+  const { dest, ...multerConfig } = mergedOptions
+  // replace dest parameter with custom storage that cleans up leaked files
+  if (dest) {
+    multerConfig.storage = multer.diskStorage({
+      destination: dest,
+      filename: filenameWithCleanup(dest),
+    })
+  }
+  return multer(multerConfig)
+}
+
+/* remove the uploaded file when an error reaches the end of the route,
+ * so route handlers don't each have to unlink on every error path
+ */
+export function multerErrorHandler(err, req, res, next) {
+  if (req.file?.path) {
+    fs.unlink(req.file.path, unlinkErr => {
+      if (unlinkErr && unlinkErr.code !== 'ENOENT') {
+        logger.warn(
+          { err: unlinkErr, uploadPath: req.file.path },
+          'error deleting uploaded file on multer error cleanup'
+        )
+      }
+    })
+  }
+  next(err)
+}