Closes #612 Co-authored-by: tusooa <tusooa@kazv.moe> Reviewed-on: https://akkoma.dev/AkkomaGang/akkoma/pulls/626 Co-authored-by: FloatingGhost <hannah@coffee-and-dreams.uk> Co-committed-by: FloatingGhost <hannah@coffee-and-dreams.uk>
		
			
				
	
	
		
			128 lines
		
	
	
	
		
			3.6 KiB
		
	
	
	
		
			Elixir
		
	
	
	
	
	
			
		
		
	
	
			128 lines
		
	
	
	
		
			3.6 KiB
		
	
	
	
		
			Elixir
		
	
	
	
	
	
# Pleroma: A lightweight social networking server
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# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
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# SPDX-License-Identifier: AGPL-3.0-only
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defmodule Pleroma.Web.Plugs.HTTPSignaturePlug do
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  import Plug.Conn
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  import Phoenix.Controller, only: [get_format: 1]
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  use Pleroma.Web, :verified_routes
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  alias Pleroma.Activity
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  alias Pleroma.Signature
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  alias Pleroma.Instances
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  require Logger
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  @cachex Pleroma.Config.get([:cachex, :provider], Cachex)
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  def init(options) do
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    options
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  end
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  def call(%{assigns: %{valid_signature: true}} = conn, _opts) do
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    conn
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  end
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  def call(conn, _opts) do
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    if get_format(conn) in ["json", "activity+json"] do
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      conn
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      |> maybe_assign_valid_signature()
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      |> maybe_require_signature()
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    else
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      conn
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    end
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  end
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  def route_aliases(%{path_info: ["objects", id], query_string: query_string}) do
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    ap_id = url(~p[/objects/#{id}])
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    with %Activity{} = activity <- Activity.get_by_object_ap_id_with_object(ap_id) do
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      [~p"/notice/#{activity.id}", "/notice/#{activity.id}?#{query_string}"]
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    else
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      _ -> []
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    end
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  end
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  def route_aliases(_), do: []
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  defp assign_valid_signature_on_route_aliases(conn, []), do: conn
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  defp assign_valid_signature_on_route_aliases(%{assigns: %{valid_signature: true}} = conn, _),
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    do: conn
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  defp assign_valid_signature_on_route_aliases(conn, [path | rest]) do
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    request_target = String.downcase("#{conn.method}") <> " #{path}"
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    conn =
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      conn
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      |> put_req_header("(request-target)", request_target)
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      |> case do
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        %{assigns: %{digest: digest}} = conn -> put_req_header(conn, "digest", digest)
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        conn -> conn
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      end
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    conn
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    |> assign(:valid_signature, HTTPSignatures.validate_conn(conn))
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    |> assign(:signature_actor_id, signature_host(conn))
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    |> assign_valid_signature_on_route_aliases(rest)
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  end
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  defp maybe_assign_valid_signature(conn) do
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    if has_signature_header?(conn) do
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      # set (request-target) header to the appropriate value
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      # we also replace the digest header with the one we computed
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      possible_paths =
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        route_aliases(conn) ++ [conn.request_path, conn.request_path <> "?#{conn.query_string}"]
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      assign_valid_signature_on_route_aliases(conn, possible_paths)
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    else
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      Logger.debug("No signature header!")
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      conn
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    end
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  end
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  defp has_signature_header?(conn) do
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    conn |> get_req_header("signature") |> Enum.at(0, false)
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  end
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  defp maybe_require_signature(
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         %{assigns: %{valid_signature: true, signature_actor_id: actor_id}} = conn
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       ) do
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    # inboxes implicitly need http signatures for authentication
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    # so we don't really know if the instance will have broken federation after
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    # we turn on authorized_fetch_mode.
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    #
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    # to "check" this is a signed fetch, verify if method is GET
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    if conn.method == "GET" do
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      actor_host = URI.parse(actor_id).host
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      case @cachex.get(:request_signatures_cache, actor_host) do
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        {:ok, nil} ->
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          Logger.debug("Successful signature from #{actor_host}")
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          Instances.set_request_signatures(actor_host)
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          @cachex.put(:request_signatures_cache, actor_host, true)
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        {:ok, true} ->
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          :noop
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        any ->
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          Logger.warning(
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            "expected request signature cache to return a boolean, instead got #{inspect(any)}"
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          )
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      end
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    end
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    conn
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  end
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  defp maybe_require_signature(conn), do: conn
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  defp signature_host(conn) do
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    with %{"keyId" => kid} <- HTTPSignatures.signature_for_conn(conn),
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         {:ok, actor_id} <- Signature.key_id_to_actor_id(kid) do
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      actor_id
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    else
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      e ->
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        {:error, e}
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    end
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  end
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end
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