mobilizon/lib/web/plugs/http_security_plug.ex

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# Portions of this file are derived from Pleroma:
# Pleroma: A lightweight social networking server
# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Mobilizon.Web.Plugs.HTTPSecurityPlug do
@moduledoc """
A plug to setup some HTTP security-related headers, like CSP
"""
alias Mobilizon.Config
import Plug.Conn
require Logger
def init(opts), do: opts
def call(conn, options \\ []) do
if Config.get([:http_security, :enabled]) do
conn
|> merge_resp_headers(headers(options))
|> maybe_send_sts_header(Config.get([:http_security, :sts]))
else
conn
end
end
defp headers(options) do
referrer_policy =
Keyword.get(options, :referrer_policy, Config.get([:http_security, :referrer_policy]))
[
{"x-xss-protection", "0"},
{"x-frame-options", "DENY"},
{"x-content-type-options", "nosniff"},
{"referrer-policy", referrer_policy},
{"content-security-policy", csp_string(options)}
]
end
@static_csp_rules [
"default-src 'none'",
"base-uri 'self'",
"manifest-src 'self'"
]
@csp_start [Enum.join(@static_csp_rules, ";") <> ";"]
@img_src "img-src 'self' data: blob: "
@media_src "media-src 'self' "
# Connect-src is available for any origin (*) because of webfinger query to redirect to content
@connect_src "connect-src 'self' * blob: "
# unsafe-eval is because of JS issues with regenerator-runtime
@script_src "script-src 'self' 'unsafe-eval' "
@style_src "style-src 'self' "
@font_src "font-src 'self' "
defp csp_string(options) do
scheme = Keyword.get(options, :scheme, Config.get([Pleroma.Web.Endpoint, :url])[:scheme])
static_url = Mobilizon.Web.Endpoint.static_url()
websocket_url = Mobilizon.Web.Endpoint.websocket_url()
img_src = [@img_src | get_csp_config(:img_src, options)]
media_src = [@media_src | get_csp_config(:media_src, options)]
connect_src = [
@connect_src,
static_url,
?\s,
websocket_url,
?\s,
get_csp_config(:connect_src, options)
]
script_src =
if Config.get(:env) == :dev do
[@script_src, "'unsafe-inline' "]
else
[
@script_src,
"'sha256-4RS22DYeB7U14dra4KcQYxmwt5HkOInieXK1NUMBmQI=' "
]
end
script_src = [script_src | get_csp_config(:script_src, options)]
style_src =
if Config.get(:env) == :dev, do: [@style_src | "'unsafe-inline' "], else: @style_src
style_src = [style_src | get_csp_config(:style_src, options)]
font_src = [@font_src | get_csp_config(:font_src, options)]
frame_src = if Config.get(:env) == :dev, do: "frame-src 'self' ", else: "frame-src 'none' "
frame_src = [frame_src | get_csp_config(:frame_src, options)]
frame_ancestors =
if Config.get(:env) == :dev, do: "frame-ancestors 'self' ", else: "frame-ancestors 'none' "
frame_ancestors = [frame_ancestors | get_csp_config(:frame_ancestors, options)]
insecure = if scheme == "https", do: "upgrade-insecure-requests"
@csp_start
|> add_csp_param(script_src)
|> add_csp_param(style_src)
|> add_csp_param(connect_src)
|> add_csp_param(img_src)
|> add_csp_param(media_src)
|> add_csp_param(font_src)
|> add_csp_param(frame_src)
|> add_csp_param(frame_ancestors)
|> add_csp_param(insecure)
|> to_string()
end
defp add_csp_param(csp_iodata, nil), do: csp_iodata
defp add_csp_param(csp_iodata, param), do: [[param, ?;] | csp_iodata]
defp maybe_send_sts_header(conn, true) do
max_age_sts = Config.get([:http_security, :sts_max_age])
merge_resp_headers(conn, [
{"strict-transport-security", "max-age=#{max_age_sts}; includeSubDomains"}
])
end
defp maybe_send_sts_header(conn, _), do: conn
defp get_csp_config(type, options) do
options
|> Keyword.get(type, Config.get([:http_security, :csp_policy, type]))
|> Enum.join(" ")
end
end