media_proxy: CSP, content-disposition

* Adds CSP headers to the media proxy endpoint

* Sends `content-disposition: attachment; …` for non-image/video/audio
content types

The default list can be overwritten with `:media_proxy,
:safe_content_types` in the configuration.

* Also now appends the filename to the proxy URL (fixes some mobile apps,
it was requested a while ago)
This commit is contained in:
href 2018-11-13 15:58:02 +01:00
parent 22d20c497b
commit 9b553a1087
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GPG key ID: EE8296C1A152C325
3 changed files with 46 additions and 5 deletions

View file

@ -11,15 +11,47 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyController do
error: "public, must-revalidate, max-age=160"
}
def remote(conn, %{"sig" => sig, "url" => url}) do
# Content-types that will not be returned as content-disposition attachments
# Override with :media_proxy, :safe_content_types in the configuration
@safe_content_types [
"image/gif",
"image/jpeg",
"image/jpg",
"image/png",
"image/svg+xml",
"audio/mpeg",
"audio/mp3",
"video/webm",
"video/mp4"
]
def remote(conn, params = %{"sig" => sig, "url" => url}) do
config = Application.get_env(:pleroma, :media_proxy, [])
with true <- Keyword.get(config, :enabled, false),
{:ok, url} <- Pleroma.Web.MediaProxy.decode_url(sig, url),
{:ok, content_type, body} <- proxy_request(url) do
filename <- Path.basename(url),
true <-
if(Map.get(params, "filename"),
do: filename == Path.basename(conn.request_path),
else: true
),
{:ok, content_type, body} <- proxy_request(url),
safe_content_type <-
Enum.member?(
Keyword.get(config, :safe_content_types, @safe_content_types),
content_type
) do
conn
|> put_resp_content_type(content_type)
|> set_cache_header(:default)
|> put_resp_header(
"content-security-policy",
"default-src 'none'; style-src 'unsafe-inline'; media-src data:; img-src 'self' data:"
)
|> put_resp_header("x-xss-protection", "1; mode=block")
|> put_resp_header("x-content-type-options", "nosniff")
|> put_attachement_header(safe_content_type, filename)
|> send_resp(200, body)
else
false ->
@ -92,6 +124,12 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyController do
# TODO: the body is passed here as well because some hosts do not provide a content-type.
# At some point we may want to use magic numbers to discover the content-type and reply a proper one.
defp proxy_request_content_type(headers, _body) do
headers["Content-Type"] || headers["content-type"] || "image/jpeg"
headers["Content-Type"] || headers["content-type"] || "application/octet-stream"
end
defp put_attachement_header(conn, true, _), do: conn
defp put_attachement_header(conn, false, filename) do
put_resp_header(conn, "content-disposition", "attachment; filename='#{filename}'")
end
end

View file

@ -15,7 +15,10 @@ defmodule Pleroma.Web.MediaProxy do
base64 = Base.url_encode64(url, @base64_opts)
sig = :crypto.hmac(:sha, secret, base64)
sig64 = sig |> Base.url_encode64(@base64_opts)
Keyword.get(config, :base_url, Pleroma.Web.base_url()) <> "/proxy/#{sig64}/#{base64}"
filename = Path.basename(url)
Keyword.get(config, :base_url, Pleroma.Web.base_url()) <>
"/proxy/#{sig64}/#{base64}/#{filename}"
end
end

View file

@ -378,12 +378,12 @@ defmodule Pleroma.Web.Router do
end
pipeline :remote_media do
plug(:accepts, ["html"])
end
scope "/proxy/", Pleroma.Web.MediaProxy do
pipe_through(:remote_media)
get("/:sig/:url", MediaProxyController, :remote)
get("/:sig/:url/:filename", MediaProxyController, :remote)
end
scope "/", Fallback do