140 lines
4.4 KiB
Elixir
140 lines
4.4 KiB
Elixir
# Pleroma: A lightweight social networking server
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# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
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# SPDX-License-Identifier: AGPL-3.0-only
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defmodule Pleroma.Signature do
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@behaviour HTTPSignatures.Adapter
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alias Pleroma.EctoType.ActivityPub.ObjectValidators
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alias Pleroma.Keys
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alias Pleroma.User
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alias Pleroma.Web.ActivityPub.ActivityPub
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import Plug.Conn, only: [put_req_header: 3]
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@http_signatures_impl Application.compile_env(
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:pleroma,
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[__MODULE__, :http_signatures_impl],
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HTTPSignatures
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)
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@known_suffixes ["/publickey", "/main-key"]
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def key_id_to_actor_id(key_id) do
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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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|> remove_suffix(@known_suffixes)
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maybe_ap_id = URI.to_string(uri)
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case ObjectValidators.ObjectID.cast(maybe_ap_id) do
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{:ok, ap_id} ->
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{:ok, ap_id}
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_ ->
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case Pleroma.Web.WebFinger.finger(maybe_ap_id) do
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{:ok, %{"ap_id" => ap_id}} -> {:ok, ap_id}
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_ -> {:error, maybe_ap_id}
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end
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end
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end
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defp remove_suffix(uri, [test | rest]) do
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if not is_nil(uri.path) and String.ends_with?(uri.path, test) do
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Map.put(uri, :path, String.replace(uri.path, test, ""))
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else
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remove_suffix(uri, rest)
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end
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end
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defp remove_suffix(uri, []), do: uri
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def fetch_public_key(conn) do
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with {:ok, actor_id} <- get_actor_id(conn),
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{:ok, public_key} <- User.get_public_key_for_ap_id(actor_id) do
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{:ok, public_key}
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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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def refetch_public_key(conn) do
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with {:ok, actor_id} <- get_actor_id(conn),
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{:ok, _user} <- ActivityPub.make_user_from_ap_id(actor_id),
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{:ok, public_key} <- User.get_public_key_for_ap_id(actor_id) do
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{:ok, public_key}
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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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def get_actor_id(conn) do
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with %{"keyId" => kid} <- HTTPSignatures.signature_for_conn(conn),
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{:ok, actor_id} <- key_id_to_actor_id(kid) do
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{:ok, 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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def sign(%User{keys: keys} = user, headers) do
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with {:ok, private_key, _} <- Keys.keys_from_pem(keys) do
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HTTPSignatures.sign(private_key, user.ap_id <> "#main-key", headers)
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end
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end
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def signed_date, do: signed_date(NaiveDateTime.utc_now())
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def signed_date(%NaiveDateTime{} = date) do
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Timex.format!(date, "{WDshort}, {0D} {Mshort} {YYYY} {h24}:{m}:{s} GMT")
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end
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@spec validate_signature(Plug.Conn.t(), String.t()) :: boolean()
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def validate_signature(%Plug.Conn{} = conn, request_target) do
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# Newer drafts for HTTP signatures now use @request-target instead of the
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# old (request-target). We'll now support both for incoming signatures.
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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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|> put_req_header("@request-target", request_target)
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@http_signatures_impl.validate_conn(conn)
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end
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@spec validate_signature(Plug.Conn.t()) :: boolean()
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def validate_signature(%Plug.Conn{} = conn) do
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# This (request-target) is non-standard, but many implementations do it
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# this way due to a misinterpretation of
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# https://datatracker.ietf.org/doc/html/draft-cavage-http-signatures-06
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# "path" was interpreted as not having the query, though later examples
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# show that it must be the absolute path + query. This behavior is kept to
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# make sure most software (Pleroma itself, Mastodon, and probably others)
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# do not break.
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request_target = Enum.join([String.downcase(conn.method), conn.request_path], " ")
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# This is the proper way to build the @request-target, as expected by
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# many HTTP signature libraries, clarified in the following draft:
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# https://www.ietf.org/archive/id/draft-ietf-httpbis-message-signatures-11.html#section-2.2.6
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# It is the same as before, but containing the query part as well.
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proper_target = Enum.join([request_target, "?", conn.query_string], "")
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cond do
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# Normal, non-standard behavior but expected by Pleroma and more.
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validate_signature(conn, request_target) ->
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true
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# Has query string and the previous one failed: let's try the standard.
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conn.query_string != "" ->
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validate_signature(conn, proper_target)
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# If there's no query string and signature fails, it's rotten.
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true ->
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false
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end
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end
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end
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