akkoma/lib/pleroma/object/fetcher.ex
rinpatch 6ca709816f Fix object spoofing vulnerability in attachments
Validate the content-type of the response when fetching an object,
according to https://www.w3.org/TR/activitypub/#x3-2-retrieving-objects.

content-type headers had to be added to many mocks in order to support
this, some of this was done with a regex. While I did go over the
resulting files to check I didn't modify anything unrelated, there is a
 possibility I missed something.

Closes pleroma#1948
2020-11-12 15:25:33 +03:00

268 lines
7.7 KiB
Elixir

# Pleroma: A lightweight social networking server
# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.Object.Fetcher do
alias Pleroma.HTTP
alias Pleroma.Object
alias Pleroma.Object.Containment
alias Pleroma.Repo
alias Pleroma.Signature
alias Pleroma.Web.ActivityPub.InternalFetchActor
alias Pleroma.Web.ActivityPub.ObjectValidator
alias Pleroma.Web.ActivityPub.Transmogrifier
alias Pleroma.Web.Federator
alias Pleroma.Web.FedSockets
require Logger
require Pleroma.Constants
defp touch_changeset(changeset) do
updated_at =
NaiveDateTime.utc_now()
|> NaiveDateTime.truncate(:second)
Ecto.Changeset.put_change(changeset, :updated_at, updated_at)
end
defp maybe_reinject_internal_fields(%{data: %{} = old_data}, new_data) do
internal_fields = Map.take(old_data, Pleroma.Constants.object_internal_fields())
Map.merge(new_data, internal_fields)
end
defp maybe_reinject_internal_fields(_, new_data), do: new_data
@spec reinject_object(struct(), map()) :: {:ok, Object.t()} | {:error, any()}
defp reinject_object(%Object{data: %{"type" => "Question"}} = object, new_data) do
Logger.debug("Reinjecting object #{new_data["id"]}")
with data <- maybe_reinject_internal_fields(object, new_data),
{:ok, data, _} <- ObjectValidator.validate(data, %{}),
changeset <- Object.change(object, %{data: data}),
changeset <- touch_changeset(changeset),
{:ok, object} <- Repo.insert_or_update(changeset),
{:ok, object} <- Object.set_cache(object) do
{:ok, object}
else
e ->
Logger.error("Error while processing object: #{inspect(e)}")
{:error, e}
end
end
defp reinject_object(%Object{} = object, new_data) do
Logger.debug("Reinjecting object #{new_data["id"]}")
with new_data <- Transmogrifier.fix_object(new_data),
data <- maybe_reinject_internal_fields(object, new_data),
changeset <- Object.change(object, %{data: data}),
changeset <- touch_changeset(changeset),
{:ok, object} <- Repo.insert_or_update(changeset),
{:ok, object} <- Object.set_cache(object) do
{:ok, object}
else
e ->
Logger.error("Error while processing object: #{inspect(e)}")
{:error, e}
end
end
def refetch_object(%Object{data: %{"id" => id}} = object) do
with {:local, false} <- {:local, Object.local?(object)},
{:ok, new_data} <- fetch_and_contain_remote_object_from_id(id),
{:ok, object} <- reinject_object(object, new_data) do
{:ok, object}
else
{:local, true} -> {:ok, object}
e -> {:error, e}
end
end
# Note: will create a Create activity, which we need internally at the moment.
def fetch_object_from_id(id, options \\ []) do
with {_, nil} <- {:fetch_object, Object.get_cached_by_ap_id(id)},
{_, true} <- {:allowed_depth, Federator.allowed_thread_distance?(options[:depth])},
{_, {:ok, data}} <- {:fetch, fetch_and_contain_remote_object_from_id(id)},
{_, nil} <- {:normalize, Object.normalize(data, false)},
params <- prepare_activity_params(data),
{_, :ok} <- {:containment, Containment.contain_origin(id, params)},
{_, {:ok, activity}} <-
{:transmogrifier, Transmogrifier.handle_incoming(params, options)},
{_, _data, %Object{} = object} <-
{:object, data, Object.normalize(activity, false)} do
{:ok, object}
else
{:allowed_depth, false} ->
{:error, "Max thread distance exceeded."}
{:containment, _} ->
{:error, "Object containment failed."}
{:transmogrifier, {:error, {:reject, e}}} ->
{:reject, e}
{:transmogrifier, _} = e ->
{:error, e}
{:object, data, nil} ->
reinject_object(%Object{}, data)
{:normalize, object = %Object{}} ->
{:ok, object}
{:fetch_object, %Object{} = object} ->
{:ok, object}
{:fetch, {:error, error}} ->
{:error, error}
e ->
e
end
end
defp prepare_activity_params(data) do
%{
"type" => "Create",
"to" => data["to"] || [],
"cc" => data["cc"] || [],
# Should we seriously keep this attributedTo thing?
"actor" => data["actor"] || data["attributedTo"],
"object" => data
}
end
def fetch_object_from_id!(id, options \\ []) do
with {:ok, object} <- fetch_object_from_id(id, options) do
object
else
{:error, %Tesla.Mock.Error{}} ->
nil
{:error, "Object has been deleted"} ->
nil
{:reject, reason} ->
Logger.info("Rejected #{id} while fetching: #{inspect(reason)}")
nil
e ->
Logger.error("Error while fetching #{id}: #{inspect(e)}")
nil
end
end
defp make_signature(id, date) do
uri = URI.parse(id)
signature =
InternalFetchActor.get_actor()
|> Signature.sign(%{
"(request-target)": "get #{uri.path}",
host: uri.host,
date: date
})
{"signature", signature}
end
defp sign_fetch(headers, id, date) do
if Pleroma.Config.get([:activitypub, :sign_object_fetches]) do
[make_signature(id, date) | headers]
else
headers
end
end
defp maybe_date_fetch(headers, date) do
if Pleroma.Config.get([:activitypub, :sign_object_fetches]) do
[{"date", date} | headers]
else
headers
end
end
def fetch_and_contain_remote_object_from_id(prm, opts \\ [])
def fetch_and_contain_remote_object_from_id(%{"id" => id}, opts),
do: fetch_and_contain_remote_object_from_id(id, opts)
def fetch_and_contain_remote_object_from_id(id, opts) when is_binary(id) do
Logger.debug("Fetching object #{id} via AP")
with {:scheme, true} <- {:scheme, String.starts_with?(id, "http")},
{:ok, body} <- get_object(id, opts),
{:ok, data} <- safe_json_decode(body),
:ok <- Containment.contain_origin_from_id(id, data) do
{:ok, data}
else
{:scheme, _} ->
{:error, "Unsupported URI scheme"}
{:error, e} ->
{:error, e}
e ->
{:error, e}
end
end
def fetch_and_contain_remote_object_from_id(_id, _opts),
do: {:error, "id must be a string"}
defp get_object(id, opts) do
with false <- Keyword.get(opts, :force_http, false),
{:ok, fedsocket} <- FedSockets.get_or_create_fed_socket(id) do
Logger.debug("fetching via fedsocket - #{inspect(id)}")
FedSockets.fetch(fedsocket, id)
else
_other ->
Logger.debug("fetching via http - #{inspect(id)}")
get_object_http(id)
end
end
defp get_object_http(id) do
date = Pleroma.Signature.signed_date()
headers =
[{"accept", "application/activity+json"}]
|> maybe_date_fetch(date)
|> sign_fetch(id, date)
case HTTP.get(id, headers) do
{:ok, %{body: body, status: code, headers: headers}} when code in 200..299 ->
case List.keyfind(headers, "content-type", 0) do
{_, content_type} ->
case Plug.Conn.Utils.media_type(content_type) do
{:ok, "application", "activity+json", _} ->
{:ok, body}
{:ok, "application", "ld+json",
%{"profile" => "https://www.w3.org/ns/activitystreams"}} ->
{:ok, body}
_ ->
{:error, {:content_type, content_type}}
end
_ ->
{:error, {:content_type, nil}}
end
{:ok, %{status: code}} when code in [404, 410] ->
{:error, "Object has been deleted"}
{:error, e} ->
{:error, e}
e ->
{:error, e}
end
end
defp safe_json_decode(nil), do: {:ok, nil}
defp safe_json_decode(json), do: Jason.decode(json)
end