Add Signed Fetch Statistics (#312)

Close #304.

Notes:
 - This patch was made on top of Pleroma develop, so I created a separate cachex worker for request signature actions, instead of Akkoma's instance cache. If that is a merge blocker, I can attempt to move logic around for that.
 - Regarding the `has_request_signatures: true -> false` state transition: I think that is a higher level thing (resetting instance state on new instance actor key) which is separate from the changes relevant to this one.

Co-authored-by: Luna <git@l4.pm>
Reviewed-on: https://akkoma.dev/AkkomaGang/akkoma/pulls/312
Co-authored-by: @luna@f.l4.pm <akkoma@l4.pm>
Co-committed-by: @luna@f.l4.pm <akkoma@l4.pm>

lib/pleroma/application.ex

@@ -157,7 +157,8 @@ defp cachex_children do
       build_cachex("failed_proxy_url", limit: 2500),
       build_cachex("banned_urls", default_ttl: :timer.hours(24 * 30), limit: 5_000),
       build_cachex("translations", default_ttl: :timer.hours(24 * 30), limit: 2500),
-      build_cachex("instances", default_ttl: :timer.hours(24), ttl_interval: 1000, limit: 2500)
+      build_cachex("instances", default_ttl: :timer.hours(24), ttl_interval: 1000, limit: 2500),
+      build_cachex("request_signatures", default_ttl: :timer.hours(24 * 30), limit: 3000)
     ]
   end
 

lib/pleroma/instances.ex

@@ -43,4 +43,6 @@ def host(url_or_host) when is_binary(url_or_host) do
       url_or_host
     end
   end
+
+  defdelegate set_request_signatures(url_or_host), to: Instance
 end

lib/pleroma/instances/instance.ex

@@ -26,6 +26,7 @@ defmodule Pleroma.Instances.Instance do
     field(:favicon, :string)
     field(:metadata_updated_at, :naive_datetime)
     field(:nodeinfo, :map, default: %{})
+    field(:has_request_signatures, :boolean)
 
     timestamps()
   end
@@ -34,7 +35,14 @@ defmodule Pleroma.Instances.Instance do
 
   def changeset(struct, params \\ %{}) do
     struct
-    |> cast(params, [:host, :unreachable_since, :favicon, :nodeinfo, :metadata_updated_at])
+    |> cast(params, [
+      :host,
+      :unreachable_since,
+      :favicon,
+      :nodeinfo,
+      :metadata_updated_at,
+      :has_request_signatures
+    ])
     |> validate_required([:host])
     |> unique_constraint(:host)
   end
@@ -316,4 +324,24 @@ def get_cached_by_url(url_or_host) do
       end)
     end
   end
+
+  def set_request_signatures(url_or_host) when is_binary(url_or_host) do
+    host = host(url_or_host)
+    existing_record = Repo.get_by(Instance, %{host: host})
+    changes = %{has_request_signatures: true}
+
+    cond do
+      is_nil(existing_record) ->
+        %Instance{}
+        |> changeset(Map.put(changes, :host, host))
+        |> Repo.insert()
+
+      true ->
+        existing_record
+        |> changeset(changes)
+        |> Repo.update()
+    end
+  end
+
+  def set_request_signatures(_), do: {:error, :invalid_input}
 end

lib/pleroma/web/plugs/http_signature_plug.ex

@@ -7,8 +7,12 @@ defmodule Pleroma.Web.Plugs.HTTPSignaturePlug do
   import Phoenix.Controller, only: [get_format: 1, text: 2]
   alias Pleroma.Activity
   alias Pleroma.Web.Router
+  alias Pleroma.Signature
+  alias Pleroma.Instances
   require Logger
 
+  @cachex Pleroma.Config.get([:cachex, :provider], Cachex)
+
   def init(options) do
     options
   end
@@ -57,6 +61,7 @@ defp assign_valid_signature_on_route_aliases(conn, [path | rest]) do
 
     conn
     |> assign(:valid_signature, HTTPSignatures.validate_conn(conn))
+    |> assign(:signature_actor_id, signature_host(conn))
     |> assign_valid_signature_on_route_aliases(rest)
   end
 
@@ -78,6 +83,36 @@ defp has_signature_header?(conn) do
     conn |> get_req_header("signature") |> Enum.at(0, false)
   end
 
+  defp maybe_require_signature(
+         %{assigns: %{valid_signature: true, signature_actor_id: actor_id}} = conn
+       ) do
+    # inboxes implicitly need http signatures for authentication
+    # so we don't really know if the instance will have broken federation after
+    # we turn on authorized_fetch_mode.
+    #
+    # to "check" this is a signed fetch, verify if method is GET
+    if conn.method == "GET" do
+      actor_host = URI.parse(actor_id).host
+
+      case @cachex.get(:request_signatures_cache, actor_host) do
+        {:ok, nil} ->
+          Logger.debug("Successful signature from #{actor_host}")
+          Instances.set_request_signatures(actor_host)
+          @cachex.put(:request_signatures_cache, actor_host, true)
+
+        {:ok, true} ->
+          :noop
+
+        any ->
+          Logger.warn(
+            "expected request signature cache to return a boolean, instead got #{inspect(any)}"
+          )
+      end
+    end
+
+    conn
+  end
+
   defp maybe_require_signature(%{assigns: %{valid_signature: true}} = conn), do: conn
 
   defp maybe_require_signature(conn) do
@@ -90,4 +125,14 @@ defp maybe_require_signature(conn) do
       conn
     end
   end
+
+  defp signature_host(conn) do
+    with %{"keyId" => kid} <- HTTPSignatures.signature_for_conn(conn),
+         {:ok, actor_id} <- Signature.key_id_to_actor_id(kid) do
+      actor_id
+    else
+      e ->
+        {:error, e}
+    end
+  end
 end

priv/repo/migrations/20221123221956_add_has_request_signatures.exs

@@ -0,0 +1,9 @@
+defmodule Pleroma.Repo.Migrations.AddHasRequestSignatures do
+  use Ecto.Migration
+
+  def change do
+    alter table(:instances) do
+      add(:has_request_signatures, :boolean, default: false, null: false)
+    end
+  end
+end

test/pleroma/instances_test.exs

@@ -4,6 +4,7 @@
 
 defmodule Pleroma.InstancesTest do
   alias Pleroma.Instances
+  alias Pleroma.Instances.Instance
 
   use Pleroma.DataCase
 
@@ -121,4 +122,21 @@ test "keeps unreachable url or host unreachable" do
       refute Instances.reachable?(host)
     end
   end
+
+  describe "set_request_signatures/1" do
+    test "sets instance has request signatures" do
+      host = "domain.com"
+
+      {:ok, instance} = Instances.set_request_signatures(host)
+      assert instance.has_request_signatures
+
+      {:ok, cached_instance} = Instance.get_cached_by_url(host)
+      assert cached_instance.has_request_signatures
+    end
+
+    test "returns error status on non-binary input" do
+      assert {:error, _} = Instances.set_request_signatures(nil)
+      assert {:error, _} = Instances.set_request_signatures(1)
+    end
+  end
 end

test/pleroma/web/plugs/http_signature_plug_test.exs

@@ -1,21 +1,50 @@
 # Pleroma: A lightweight social networking server
-# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
+# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Web.Plugs.HTTPSignaturePlugTest do
-  use Pleroma.Web.ConnCase
+  use Pleroma.Web.ConnCase, async: false
   import Pleroma.Factory
   alias Pleroma.Web.Plugs.HTTPSignaturePlug
+  alias Pleroma.Instances.Instance
+  alias Pleroma.Repo
 
   import Plug.Conn
   import Phoenix.Controller, only: [put_format: 2]
   import Mock
 
-  test "it call HTTPSignatures to check validity if the actor sighed it" do
+  setup_with_mocks([
+    {HTTPSignatures, [],
+     [
+       signature_for_conn: fn _ ->
+         %{"keyId" => "http://mastodon.example.org/users/admin#main-key"}
+       end,
+       validate_conn: fn conn ->
+         Map.get(conn.assigns, :valid_signature, true)
+       end
+     ]}
+  ]) do
+    :ok
+  end
+
+  defp submit_to_plug(host), do: submit_to_plug(host, :get, "/doesntmattter")
+
+  defp submit_to_plug(host, method, path) do
+    params = %{"actor" => "http://#{host}/users/admin"}
+
+    build_conn(method, path, params)
+    |> put_req_header(
+      "signature",
+      "keyId=\"http://#{host}/users/admin#main-key"
+    )
+    |> put_format("activity+json")
+    |> HTTPSignaturePlug.call(%{})
+  end
+
+  test "it call HTTPSignatures to check validity if the actor signed it" do
     params = %{"actor" => "http://mastodon.example.org/users/admin"}
     conn = build_conn(:get, "/doesntmattter", params)
 
-    with_mock HTTPSignatures, validate_conn: fn _ -> true end do
     conn =
       conn
       |> put_req_header(
@@ -26,9 +55,36 @@ test "it call HTTPSignatures to check validity if the actor sighed it" do
       |> HTTPSignaturePlug.call(%{})
 
     assert conn.assigns.valid_signature == true
+    assert conn.assigns.signature_actor_id == params["actor"]
     assert conn.halted == false
     assert called(HTTPSignatures.validate_conn(:_))
   end
+
+  test "it sets request signatures property on the instance" do
+    host = "mastodon.example.org"
+    conn = submit_to_plug(host)
+    assert conn.assigns.valid_signature == true
+    instance = Repo.get_by(Instance, %{host: host})
+    assert instance.has_request_signatures
+  end
+
+  test "it does not set request signatures property on the instance when using inbox" do
+    host = "mastodon.example.org"
+    conn = submit_to_plug(host, :post, "/inbox")
+    assert conn.assigns.valid_signature == true
+
+    # we don't even create the instance entry if its just POST /inbox
+    refute Repo.get_by(Instance, %{host: host})
+  end
+
+  test "it does not set request signatures property on the instance when its cached" do
+    host = "mastodon.example.org"
+    Cachex.put(:request_signatures_cache, host, true)
+    conn = submit_to_plug(host)
+    assert conn.assigns.valid_signature == true
+
+    # we don't even create the instance entry if it was already done
+    refute Repo.get_by(Instance, %{host: host})
   end
 
   describe "requires a signature when `authorized_fetch_mode` is enabled" do
@@ -41,10 +97,10 @@ test "it call HTTPSignatures to check validity if the actor sighed it" do
       [conn: conn]
     end
 
-    test "when signature header is present", %{conn: conn} do
-      with_mock HTTPSignatures, validate_conn: fn _ -> false end do
+    test "and signature is present and incorrect", %{conn: conn} do
       conn =
         conn
+        |> assign(:valid_signature, false)
         |> put_req_header(
           "signature",
           "keyId=\"http://mastodon.example.org/users/admin#main-key"
@@ -59,7 +115,7 @@ test "when signature header is present", %{conn: conn} do
       assert called(HTTPSignatures.validate_conn(:_))
     end
 
-      with_mock HTTPSignatures, validate_conn: fn _ -> true end do
+    test "and signature is correct", %{conn: conn} do
       conn =
         conn
         |> put_req_header(
@@ -72,9 +128,8 @@ test "when signature header is present", %{conn: conn} do
       assert conn.halted == false
       assert called(HTTPSignatures.validate_conn(:_))
     end
-    end
 
-    test "halts the connection when `signature` header is not present", %{conn: conn} do
+    test "and halts the connection when `signature` header is not present", %{conn: conn} do
       conn = HTTPSignaturePlug.call(conn, %{})
       assert conn.assigns[:valid_signature] == nil
       assert conn.halted == true
@@ -82,6 +137,7 @@ test "halts the connection when `signature` header is not present", %{conn: conn
       assert conn.state == :sent
       assert conn.resp_body == "Request not signed"
     end
+  end
 
   test "aliases redirected /object endpoints", _ do
     obj = insert(:note)
@@ -93,5 +149,4 @@ test "aliases redirected /object endpoints", _ do
     assert ["/notice/#{act.id}", "/notice/#{act.id}?actor=someparam"] ==
              HTTPSignaturePlug.route_aliases(conn)
   end
-  end
 end