147 lines
4.6 KiB
Elixir
147 lines
4.6 KiB
Elixir
# Portions of this file are derived from Pleroma:
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# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social>
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# SPDX-License-Identifier: AGPL-3.0-only
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# Upstream: https://git.pleroma.social/pleroma/pleroma/blob/develop/lib/pleroma/signature.ex
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defmodule Mobilizon.Federation.HTTPSignatures.Signature do
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@moduledoc """
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Adapter for the `HTTPSignatures` lib that handles signing and providing public keys to verify HTTPSignatures
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"""
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@behaviour HTTPSignatures.Adapter
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alias Mobilizon.Actors.Actor
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alias Mobilizon.Federation.ActivityPub.Actor, as: ActivityPubActor
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alias Mobilizon.Service.ErrorReporting.Sentry
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require Logger
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@spec key_id_to_actor_url(String.t()) :: String.t()
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def key_id_to_actor_url(key_id) do
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%URI{path: path} =
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uri =
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key_id
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|> URI.parse()
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|> Map.put(:fragment, nil)
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uri =
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if is_nil(path) do
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uri
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else
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%URI{uri | path: String.trim_trailing(path, "/publickey")}
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end
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URI.to_string(uri)
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end
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@doc """
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Convert internal PEM encoded keys to public key format.
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"""
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@spec prepare_public_key(String.t()) :: {:ok, tuple} | {:error, :pem_decode_error}
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def prepare_public_key(public_key_code) do
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case :public_key.pem_decode(public_key_code) do
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[public_key_entry] ->
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{:ok, :public_key.pem_entry_decode(public_key_entry)}
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_ ->
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{:error, :pem_decode_error}
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end
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end
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# Gets a public key for a given ActivityPub actor ID (url).
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@spec get_public_key_for_url(String.t()) ::
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{:ok, String.t()}
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| {:error, :actor_fetch_error | :pem_decode_error | :actor_not_fetchable}
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defp get_public_key_for_url(url) do
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case ActivityPubActor.get_or_fetch_actor_by_url(url) do
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{:ok, %Actor{keys: keys}} ->
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case prepare_public_key(keys) do
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{:ok, public_key} ->
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{:ok, public_key}
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{:error, :pem_decode_error} ->
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Logger.error("Error while decoding PEM")
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{:error, :pem_decode_error}
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end
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{:error, err} ->
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Sentry.capture_message("Unable to fetch actor, so no keys for you",
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extra: %{url: url}
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)
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Logger.error("Unable to fetch actor, so no keys for you")
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Logger.error(inspect(err))
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{:error, :actor_fetch_error}
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end
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end
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@spec fetch_public_key(Plug.Conn.t()) ::
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{:ok, String.t()}
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| {:error,
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:actor_fetch_error | :actor_not_fetchable | :pem_decode_error | :no_signature_in_conn}
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def fetch_public_key(conn) do
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case HTTPSignatures.signature_for_conn(conn) do
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%{"keyId" => kid} ->
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actor_id = key_id_to_actor_url(kid)
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Logger.debug("Fetching public key for #{actor_id}")
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get_public_key_for_url(actor_id)
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_ ->
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{:error, :no_signature_in_conn}
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end
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end
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@spec refetch_public_key(Plug.Conn.t()) ::
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{:ok, String.t()}
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| {:error, :actor_fetch_error | :actor_not_fetchable | :pem_decode_error,
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:actor_is_local}
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def refetch_public_key(conn) do
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%{"keyId" => kid} = HTTPSignatures.signature_for_conn(conn)
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actor_id = key_id_to_actor_url(kid)
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Logger.debug("Refetching public key for #{actor_id}")
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with {:ok, _actor} <- ActivityPubActor.make_actor_from_url(actor_id) do
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get_public_key_for_url(actor_id)
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end
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end
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@spec sign(Actor.t(), map()) :: String.t() | {:error, :pem_decode_error} | no_return
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def sign(%Actor{domain: domain, keys: keys} = actor, headers) when is_nil(domain) do
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Logger.debug("Signing a payload on behalf of #{actor.url}")
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Logger.debug("headers")
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Logger.debug(inspect(headers))
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case prepare_public_key(keys) do
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{:ok, key} ->
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HTTPSignatures.sign(key, actor.url <> "#main-key", headers)
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{:error, :pem_decode_error} ->
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raise ArgumentError, message: "Failed to prepare public keys for #{actor.url}"
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end
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end
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def sign(%Actor{url: url}, _) do
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Logger.error("Can't do a signature on remote actor #{url}")
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raise ArgumentError, message: "Can't do a signature on remote actor #{url}"
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end
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@spec generate_date_header :: String.t()
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def generate_date_header, do: generate_date_header(NaiveDateTime.utc_now())
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@spec generate_date_header(NaiveDateTime.t()) :: String.t()
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def generate_date_header(%NaiveDateTime{} = date) do
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Timex.lformat!(date, "{WDshort}, {0D} {Mshort} {YYYY} {h24}:{m}:{s} GMT", "en")
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end
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@spec generate_request_target(String.t(), String.t()) :: String.t()
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def generate_request_target(method, path), do: "#{method} #{path}"
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@spec build_digest(String.t()) :: String.t()
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def build_digest(body) do
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"SHA-256=#{:sha256 |> :crypto.hash(body) |> Base.encode64()}"
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end
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end
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