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
alias Mobilizon.Service.{FrontEndAnalytics, GlobalSearch, Pictures}
alias Mobilizon.Web.Endpoint
import Plug.Conn
require Logger
@spec init(any()) :: any()
def init(opts), do: opts
@spec call(Plug.Conn.t(), Keyword.t()) :: Plug.Conn.t()
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], false))
else
conn
end
end
@spec headers(Keyword.t()) :: list({String.t(), String.t()})
defp headers(options) do
referrer_policy =
Keyword.get(options, :referrer_policy, Config.get([:http_security, :referrer_policy]))
report_uri = Config.get([:http_security, :report_uri])
headers = [
{"x-xss-protection", "0"},
{"x-frame-options", "DENY"},
{"x-content-type-options", "nosniff"},
{"referrer-policy", referrer_policy},
{"content-security-policy", csp_string(options)}
]
if report_uri do
report_group = %{
"group" => "csp-endpoint",
"max-age" => 10_886_400,
"endpoints" => [
%{"url" => report_uri}
]
}
[
{"report-to", Jason.encode!(report_group)},
{"reporting-endpoints", "csp-endpoint=\"#{report_uri}\""} | headers
]
else
headers
end
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' "
@spec csp_string(Keyword.t()) :: String.t()
defp csp_string(options) do
scheme = Keyword.get(options, :scheme, Config.get([Endpoint, :url])[:scheme])
static_url = Endpoint.static_url()
websocket_url = Endpoint.websocket_url()
report_uri = Config.get([:http_security, :report_uri])
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=' ",
"'sha256-zJdRXhLWm9NGI6BFr+sNmHBBrjAdJdFr7MpUq0EwK58=' "
]
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)]
report = if report_uri, do: ["report-uri ", report_uri, " ; report-to csp-endpoint"]
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)
|> add_csp_param(report)
|> to_string()
end
@spec add_csp_param(iodata(), iodata() | nil) :: list()
defp add_csp_param(csp_iodata, nil), do: csp_iodata
defp add_csp_param(csp_iodata, param), do: [[param, ?;] | csp_iodata]
@spec maybe_send_sts_header(Plug.Conn.t(), boolean()) :: Plug.Conn.t()
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, false), do: conn
@spec get_csp_config(atom(), Keyword.t()) :: iodata()
defp get_csp_config(type, options) do
config_policy = Keyword.get(options, type, Config.get([:http_security, :csp_policy, type]))
front_end_analytics_policy = [Keyword.get(FrontEndAnalytics.csp(), type, [])]
global_search_policy = [Keyword.get(GlobalSearch.service().csp(), type, [])]
pictures_policy = [Keyword.get(Pictures.service().csp(), type, [])]
resource_providers = Config.get([Mobilizon.Service.ResourceProviders, :csp_policy, type], [])
Enum.join(
config_policy ++
front_end_analytics_policy ++
global_search_policy ++ pictures_policy ++ resource_providers,
" "
)
end
end