1
0
Fork 0
mirror of https://github.com/rails/rails.git synced 2022-11-09 12:12:34 -05:00
rails--rails/activestorage/lib/active_storage.rb
Rosa Gutierrez 06ab7b27ea Prevent content type and disposition bypass in storage service URLs
* Force content-type to binary on service urls for relevant content types

We have a list of content types that must be forcibly served as binary,
but in practice this only means to serve them as attachment always. We
should also set the Content-Type to the configured binary type.

As a bonus: add text/cache-manifest to the list of content types to be
served as binary by default.

* Store content-disposition and content-type in GCS

Forcing these in the service_url when serving the file works fine for S3
and Azure, since these services include params in the signature.
However, GCS specifically excludes response-content-disposition and
response-content-type from the signature, which means an attacker can
modify these and have files that should be served as text/plain attachments
served as inline HTML for example. This makes our attempt to force
specific files to be served as binary and as attachment can be easily
bypassed.

The only way this can be forced in GCS is by storing
content-disposition and content-type in the object metadata.

* Update GCS object metadata after identifying blob

In some cases we create the blob and upload the data before identifying
the content-type, which means we can't store that in GCS right when
uploading. In these, after creating the attachment, we enqueue a job to
identify the blob, and set the content-type.

In other cases, files are uploaded to the storage service via direct
upload link. We create the blob before the direct upload, which happens
independently from the blob creation itself. We then mark the blob as
identified, but we have already the content-type we need without having
put it in the service.

In these two cases, then, we need to update the metadata in the GCS
service.

* Include content-type and disposition in the verified key for disk service

This prevents an attacker from modifying these params in the service
signed URL, which is particularly important when we want to force them
to have specific values for security reasons.

* Allow only a list of specific content types to be served inline

This is different from the content types that must be served as binary
in the sense that any content type not in this list will be always
served as attachment but with its original content type. Only types in
this list are allowed to be served either inline or as attachment.

Apart from forcing this in the service URL, for GCS we need to store the
disposition in the metadata.

Fix CVE-2018-16477.
2018-11-27 15:36:27 -05:00

64 lines
2.2 KiB
Ruby

# frozen_string_literal: true
#--
# Copyright (c) 2017-2018 David Heinemeier Hansson, Basecamp
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#++
require "active_record"
require "active_support"
require "active_support/rails"
require "active_storage/version"
require "active_storage/errors"
require "marcel"
module ActiveStorage
extend ActiveSupport::Autoload
autoload :Attached
autoload :Service
autoload :Previewer
autoload :Analyzer
mattr_accessor :logger
mattr_accessor :verifier
mattr_accessor :queue
mattr_accessor :previewers, default: []
mattr_accessor :analyzers, default: []
mattr_accessor :variant_processor, default: :mini_magick
mattr_accessor :paths, default: {}
mattr_accessor :variable_content_types, default: []
mattr_accessor :content_types_to_serve_as_binary, default: []
mattr_accessor :content_types_allowed_inline, default: []
mattr_accessor :binary_content_type, default: "application/octet-stream"
mattr_accessor :service_urls_expire_in, default: 5.minutes
mattr_accessor :routes_prefix, default: "/rails/active_storage"
module Transformers
extend ActiveSupport::Autoload
autoload :Transformer
autoload :ImageProcessingTransformer
autoload :MiniMagickTransformer
end
end