html: new module providing a configurable markup scrubbing policy

config/config.exs

@@ -76,6 +76,9 @@
   quarantined_instances: [],
   managed_config: true
 
+config :pleroma, :markup,
+  scrub_policy: HtmlSanitizeEx.Scrubber.BasicHTML
+
 config :pleroma, :fe,
   theme: "pleroma-dark",
   logo: "/static/logo.png",

lib/pleroma/html.ex

@@ -0,0 +1,14 @@
+defmodule Pleroma.HTML do
+  alias HtmlSanitizeEx.Scrubber
+
+  @markup Application.get_env(:pleroma, :markup)
+
+  def filter_tags(html) do
+    scrubber = Keyword.get(@markup, :scrub_policy)
+    html |> Scrubber.scrub(scrubber)
+  end
+
+  def strip_tags(html) do
+    html |> Scrubber.scrub(Scrubber.StripTags)
+  end
+end