overleaf/services/clsi/app/coffee/StaticServerForbidSymlinks.coffee

41 lines
1.7 KiB
CoffeeScript

Path = require("path")
fs = require("fs")
Settings = require("settings-sharelatex")
logger = require("logger-sharelatex")
url = require "url"
module.exports = ForbidSymlinks = (staticFn, root, options) ->
expressStatic = staticFn root, options
basePath = Path.resolve(root)
return (req, res, next) ->
path = url.parse(req.url)?.pathname
# check that the path is of the form /project_id_or_name/path/to/file.log
if result = path.match(/^\/?([a-zA-Z0-9_-]+)\/(.*)/)
project_id = result[1]
file = result[2]
else
logger.warn path: path, "unrecognized file request"
return res.sendStatus(404)
# check that the file does not use a relative path
for dir in file.split('/')
if dir == '..'
logger.warn path: path, "attempt to use a relative path"
return res.sendStatus(404)
# check that the requested path is normalized
requestedFsPath = "#{basePath}/#{project_id}/#{file}"
if requestedFsPath != Path.normalize(requestedFsPath)
logger.error path: requestedFsPath, "requestedFsPath is not normalized"
return res.sendStatus(404)
# check that the requested path is not a symlink
fs.realpath requestedFsPath, (err, realFsPath)->
if err?
if err.code == 'ENOENT'
return res.sendStatus(404)
else
logger.error err:err, requestedFsPath:requestedFsPath, realFsPath:realFsPath, path: req.params[0], project_id: req.params.project_id, "error checking file access"
return res.sendStatus(500)
else if requestedFsPath != realFsPath
logger.warn requestedFsPath:requestedFsPath, realFsPath:realFsPath, path: req.params[0], project_id: req.params.project_id, "trying to access a different file (symlink), aborting"
return res.sendStatus(404)
else
expressStatic(req, res, next)