akkoma/lib/pleroma/web/activity_pub/object_validators/user_validator.ex
Oneric f07eb4cb55 Sanity check fetched user data
In order to properly process incoming notes we need
to be able to map the key id back to an actor.
Also, check collections actually belong to the same server.

Key ids of Hubzilla and Bridgy samples were updated to what
modern versions of those output. If anything still uses the
old format, we would not be able to verify their posts anyway.
2024-03-25 14:05:05 -01:00

93 lines
2.6 KiB
Elixir

# Akkoma: Magically expressive social media
# Copyright © 2024 Akkoma Authors <https://akkoma.dev/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.Web.ActivityPub.ObjectValidators.UserValidator do
@moduledoc """
Checks whether ActivityPub data represents a valid user
Users don't go through the same ingest pipeline like activities or other objects.
To ensure this can only match a user and no users match in the other pipeline,
this is a separate from the generic ObjectValidator.
"""
@behaviour Pleroma.Web.ActivityPub.ObjectValidator.Validating
alias Pleroma.Object.Containment
alias Pleroma.Signature
@impl true
def validate(object, meta)
def validate(%{"type" => type, "id" => _id} = data, meta)
when type in ["Person", "Organization", "Group", "Application"] do
with :ok <- validate_pubkey(data),
:ok <- validate_inbox(data),
:ok <- contain_collection_origin(data) do
{:ok, data, meta}
else
{:error, e} -> {:error, e}
e -> {:error, e}
end
end
def validate(_, _), do: {:error, "Not a user object"}
defp mabye_validate_owner(nil, _actor), do: :ok
defp mabye_validate_owner(actor, actor), do: :ok
defp mabye_validate_owner(_owner, _actor), do: :error
defp validate_pubkey(
%{"id" => id, "publicKey" => %{"id" => pk_id, "publicKeyPem" => _key}} = data
)
when id != nil do
with {_, {:ok, kactor}} <- {:key, Signature.key_id_to_actor_id(pk_id)},
true <- id == kactor,
:ok <- mabye_validate_owner(Map.get(data, "owner"), id) do
:ok
else
{:key, _} ->
{:error, "Unable to determine actor id from key id"}
false ->
{:error, "Key id does not relate to user id"}
_ ->
{:error, "Actor does not own its public key"}
end
end
# pubkey is optional atm
defp validate_pubkey(_data), do: :ok
defp validate_inbox(%{"id" => id, "inbox" => inbox}) do
case Containment.same_origin(id, inbox) do
:ok -> :ok
:error -> {:error, "Inbox on different doamin"}
end
end
defp validate_inbox(_), do: {:error, "No inbox"}
defp check_field_value(%{"id" => id} = _data, value) do
Containment.same_origin(id, value)
end
defp maybe_check_field(data, field) do
with val when val != nil <- data[field],
:ok <- check_field_value(data, val) do
:ok
else
nil -> :ok
_ -> {:error, "#{field} on different domain"}
end
end
defp contain_collection_origin(data) do
Enum.reduce(["followers", "following", "featured"], :ok, fn
field, :ok -> maybe_check_field(data, field)
_, error -> error
end)
end
end