akkoma/lib/pleroma/web/plugs/uploaded_media.ex
Oneric ba558c0c24 Limit instance emoji to image types
Else malicious emoji packs or our EmojiStealer MRF can
put payloads into the same domain as the instance itself.
Sanitising the content type should prevent proper clients
from acting on any potential payload.

Note, this does not affect the default emoji shipped with Akkoma
as they are handled by another plug. However, those are fully trusted
and thus not in needed of sanitisation.
2024-03-18 22:33:10 -01:00

127 lines
3.3 KiB
Elixir

# Pleroma: A lightweight social networking server
# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.Web.Plugs.UploadedMedia do
@moduledoc """
"""
import Plug.Conn
import Pleroma.Web.Gettext
require Logger
alias Pleroma.Web.MediaProxy
alias Pleroma.Web.Plugs.Utils
@behaviour Plug
# no slashes
@path "media"
@default_cache_control_header "public, max-age=1209600"
def init(_opts) do
static_plug_opts =
[
headers: %{"cache-control" => @default_cache_control_header},
cache_control_for_etags: @default_cache_control_header
]
|> Keyword.put(:from, "__unconfigured_media_plug")
|> Keyword.put(:at, "/__unconfigured_media_plug")
|> Plug.Static.init()
config = Pleroma.Config.get(Pleroma.Upload)
allowed_mime_types = Keyword.fetch!(config, :allowed_mime_types)
uploader = Keyword.fetch!(config, :uploader)
%{
static_plug_opts: static_plug_opts,
allowed_mime_types: allowed_mime_types,
uploader: uploader
}
end
def call(
%{request_path: <<"/", @path, "/", file::binary>>} = conn,
%{uploader: uploader} = opts
) do
conn =
case fetch_query_params(conn) do
%{query_params: %{"name" => name}} = conn ->
name = escape_header_value(name)
put_resp_header(conn, "content-disposition", ~s[inline; filename="#{name}"])
conn ->
conn
end
|> merge_resp_headers([{"content-security-policy", "sandbox"}])
with {:ok, get_method} <- uploader.get_file(file),
false <- media_is_banned(conn, get_method) do
get_media(conn, get_method, opts)
else
_ ->
conn
|> send_resp(:internal_server_error, dgettext("errors", "Failed"))
|> halt()
end
end
def call(conn, _opts), do: conn
defp media_is_banned(%{request_path: path} = _conn, {:static_dir, _}) do
MediaProxy.in_banned_urls(Pleroma.Upload.base_url() <> path)
end
defp media_is_banned(_, {:url, url}), do: MediaProxy.in_banned_urls(url)
defp media_is_banned(_, _), do: false
defp set_content_type(conn, opts, filepath) do
real_mime = MIME.from_path(filepath)
clean_mime = Utils.get_safe_mime_type(opts, real_mime)
put_resp_header(conn, "content-type", clean_mime)
end
defp get_media(conn, {:static_dir, directory}, opts) do
static_opts =
Map.get(opts, :static_plug_opts)
|> Map.put(:at, [@path])
|> Map.put(:from, directory)
|> Map.put(:set_content_type, false)
conn =
conn
|> set_content_type(opts, conn.request_path)
|> Pleroma.Web.Plugs.StaticNoCT.call(static_opts)
if conn.halted do
conn
else
conn
|> send_resp(:not_found, dgettext("errors", "Not found"))
|> halt()
end
end
defp get_media(conn, {:url, url}, _) do
conn
|> Phoenix.Controller.redirect(external: url)
|> halt()
end
defp get_media(conn, unknown, _) do
Logger.error("#{__MODULE__}: Unknown get startegy: #{inspect(unknown)}")
conn
|> send_resp(:internal_server_error, dgettext("errors", "Internal Error"))
|> halt()
end
defp escape_header_value(value) do
value
|> String.replace("\"", "\\\"")
|> String.replace("\\r", "")
|> String.replace("\\n", "")
end
end