akkoma/lib/pleroma/web/plugs/mapped_signature_to_identity_plug.ex

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# 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.MappedSignatureToIdentityPlug do
alias Pleroma.Helpers.AuthHelper
alias Pleroma.Signature
alias Pleroma.User
alias Pleroma.Web.ActivityPub.Utils
import Plug.Conn
require Logger
def init(options), do: options
def call(%{assigns: %{user: %User{}}} = conn, _opts), do: conn
# if this has payload make sure it is signed by the same actor that made it
def call(%{assigns: %{valid_signature: true}, params: %{"actor" => actor}} = conn, _opts) do
with actor_id <- Utils.get_ap_id(actor),
{:user, %User{} = user} <- {:user, user_from_key_id(conn)},
{:federate, true} <- {:federate, should_federate?(user)},
{:user_match, true} <- {:user_match, user.ap_id == actor_id} do
conn
|> assign(:user, user)
|> AuthHelper.skip_oauth()
else
{:user_match, false} ->
Logger.debug("Failed to map identity from signature (payload actor mismatch)")
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Logger.debug("key_id=#{inspect(key_id_from_conn(conn))}, actor=#{inspect(actor)}")
conn
|> assign(:valid_signature, false)
# remove me once testsuite uses mapped capabilities instead of what we do now
{:user, nil} ->
Logger.debug("Failed to map identity from signature (lookup failure)")
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Logger.debug("key_id=#{inspect(key_id_from_conn(conn))}, actor=#{actor}")
conn
|> assign(:valid_signature, false)
{:federate, false} ->
Logger.debug("Identity from signature is instance blocked")
Logger.debug("key_id=#{inspect(key_id_from_conn(conn))}, actor=#{actor}")
conn
|> assign(:valid_signature, false)
end
end
# no payload, probably a signed fetch
def call(%{assigns: %{valid_signature: true}} = conn, _opts) do
with %User{} = user <- user_from_key_id(conn),
{:federate, true} <- {:federate, should_federate?(user)} do
conn
|> assign(:user, user)
|> AuthHelper.skip_oauth()
else
{:federate, false} ->
Logger.debug("Identity from signature is instance blocked")
Logger.debug("key_id=#{inspect(key_id_from_conn(conn))}")
conn
|> assign(:valid_signature, false)
nil ->
Logger.debug("Failed to map identity from signature (lookup failure)")
Logger.debug("key_id=#{inspect(key_id_from_conn(conn))}")
only_permit_user_routes(conn)
_ ->
Logger.debug("Failed to map identity from signature (no payload actor mismatch)")
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Logger.debug("key_id=#{inspect(key_id_from_conn(conn))}")
conn
|> assign(:valid_signature, false)
end
end
# no signature at all
def call(conn, _opts), do: conn
defp only_permit_user_routes(%{path_info: ["users", _]} = conn) do
conn
|> assign(:limited_ap, true)
end
defp only_permit_user_routes(conn) do
conn
|> assign(:valid_signature, false)
end
defp key_id_from_conn(conn) do
with %{"keyId" => key_id} <- HTTPSignatures.signature_for_conn(conn),
{:ok, ap_id} <- Signature.key_id_to_actor_id(key_id) do
ap_id
else
_ ->
nil
end
end
defp user_from_key_id(conn) do
with key_actor_id when is_binary(key_actor_id) <- key_id_from_conn(conn),
{:ok, %User{} = user} <- User.get_or_fetch_by_ap_id(key_actor_id) do
user
else
_ ->
nil
end
end
defp should_federate?(%User{ap_id: ap_id}), do: should_federate?(ap_id)
defp should_federate?(ap_id) do
if Pleroma.Config.get([:activitypub, :authorized_fetch_mode], false) do
Pleroma.Web.ActivityPub.Publisher.should_federate?(ap_id)
else
true
end
end
end