HTML: Compile Scrubbers on boot

This makes it possible to configure their behavior on OTP releases.

4 files changed, 209 insertions, 0 deletions

diff --git a/priv/scrubbers/default.ex b/priv/scrubbers/default.ex
new file mode 100644
index 000000000..ea0480dcd
--- /dev/null
+++ b/priv/scrubbers/default.ex
@@ -0,0 +1,93 @@
+defmodule Pleroma.HTML.Scrubber.Default do
+  @doc "The default HTML scrubbing policy: no "
+
+  require FastSanitize.Sanitizer.Meta
+  alias FastSanitize.Sanitizer.Meta
+
+  # credo:disable-for-previous-line
+  # No idea how to fix this one…
+
+  @valid_schemes Pleroma.Config.get([:uri_schemes, :valid_schemes], [])
+
+  Meta.strip_comments()
+
+  Meta.allow_tag_with_uri_attributes(:a, ["href", "data-user", "data-tag"], @valid_schemes)
+
+  Meta.allow_tag_with_this_attribute_values(:a, "class", [
+    "hashtag",
+    "u-url",
+    "mention",
+    "u-url mention",
+    "mention u-url"
+  ])
+
+  Meta.allow_tag_with_this_attribute_values(:a, "rel", [
+    "tag",
+    "nofollow",
+    "noopener",
+    "noreferrer",
+    "ugc"
+  ])
+
+  Meta.allow_tag_with_these_attributes(:a, ["name", "title"])
+
+  Meta.allow_tag_with_these_attributes(:abbr, ["title"])
+
+  Meta.allow_tag_with_these_attributes(:b, [])
+  Meta.allow_tag_with_these_attributes(:blockquote, [])
+  Meta.allow_tag_with_these_attributes(:br, [])
+  Meta.allow_tag_with_these_attributes(:code, [])
+  Meta.allow_tag_with_these_attributes(:del, [])
+  Meta.allow_tag_with_these_attributes(:em, [])
+  Meta.allow_tag_with_these_attributes(:i, [])
+  Meta.allow_tag_with_these_attributes(:li, [])
+  Meta.allow_tag_with_these_attributes(:ol, [])
+  Meta.allow_tag_with_these_attributes(:p, [])
+  Meta.allow_tag_with_these_attributes(:pre, [])
+  Meta.allow_tag_with_these_attributes(:strong, [])
+  Meta.allow_tag_with_these_attributes(:sub, [])
+  Meta.allow_tag_with_these_attributes(:sup, [])
+  Meta.allow_tag_with_these_attributes(:u, [])
+  Meta.allow_tag_with_these_attributes(:ul, [])
+
+  Meta.allow_tag_with_this_attribute_values(:span, "class", ["h-card"])
+  Meta.allow_tag_with_these_attributes(:span, [])
+
+  @allow_inline_images Pleroma.Config.get([:markup, :allow_inline_images])
+
+  if @allow_inline_images do
+    # restrict img tags to http/https only, because of MediaProxy.
+    Meta.allow_tag_with_uri_attributes(:img, ["src"], ["http", "https"])
+
+    Meta.allow_tag_with_these_attributes(:img, [
+      "width",
+      "height",
+      "class",
+      "title",
+      "alt"
+    ])
+  end
+
+  if Pleroma.Config.get([:markup, :allow_tables]) do
+    Meta.allow_tag_with_these_attributes(:table, [])
+    Meta.allow_tag_with_these_attributes(:tbody, [])
+    Meta.allow_tag_with_these_attributes(:td, [])
+    Meta.allow_tag_with_these_attributes(:th, [])
+    Meta.allow_tag_with_these_attributes(:thead, [])
+    Meta.allow_tag_with_these_attributes(:tr, [])
+  end
+
+  if Pleroma.Config.get([:markup, :allow_headings]) do
+    Meta.allow_tag_with_these_attributes(:h1, [])
+    Meta.allow_tag_with_these_attributes(:h2, [])
+    Meta.allow_tag_with_these_attributes(:h3, [])
+    Meta.allow_tag_with_these_attributes(:h4, [])
+    Meta.allow_tag_with_these_attributes(:h5, [])
+  end
+
+  if Pleroma.Config.get([:markup, :allow_fonts]) do
+    Meta.allow_tag_with_these_attributes(:font, ["face"])
+  end
+
+  Meta.strip_everything_not_covered()
+end
diff --git a/priv/scrubbers/links_only.ex b/priv/scrubbers/links_only.ex
new file mode 100644
index 000000000..b30a00589
--- /dev/null
+++ b/priv/scrubbers/links_only.ex
@@ -0,0 +1,27 @@
+defmodule Pleroma.HTML.Scrubber.LinksOnly do
+  @moduledoc """
+  An HTML scrubbing policy which limits to links only.
+  """
+
+  @valid_schemes Pleroma.Config.get([:uri_schemes, :valid_schemes], [])
+
+  require FastSanitize.Sanitizer.Meta
+  alias FastSanitize.Sanitizer.Meta
+
+  Meta.strip_comments()
+
+  # links
+  Meta.allow_tag_with_uri_attributes(:a, ["href"], @valid_schemes)
+
+  Meta.allow_tag_with_this_attribute_values(:a, "rel", [
+    "tag",
+    "nofollow",
+    "noopener",
+    "noreferrer",
+    "me",
+    "ugc"
+  ])
+
+  Meta.allow_tag_with_these_attributes(:a, ["name", "title"])
+  Meta.strip_everything_not_covered()
+end
diff --git a/priv/scrubbers/media_proxy.ex b/priv/scrubbers/media_proxy.ex
new file mode 100644
index 000000000..5dbe57666
--- /dev/null
+++ b/priv/scrubbers/media_proxy.ex
@@ -0,0 +1,32 @@
+defmodule Pleroma.HTML.Transform.MediaProxy do
+  @moduledoc "Transforms inline image URIs to use MediaProxy."
+
+  alias Pleroma.Web.MediaProxy
+
+  def before_scrub(html), do: html
+
+  def scrub_attribute(:img, {"src", "http" <> target}) do
+    media_url =
+      ("http" <> target)
+      |> MediaProxy.url()
+
+    {"src", media_url}
+  end
+
+  def scrub_attribute(_tag, attribute), do: attribute
+
+  def scrub({:img, attributes, children}) do
+    attributes =
+      attributes
+      |> Enum.map(fn attr -> scrub_attribute(:img, attr) end)
+      |> Enum.reject(&is_nil(&1))
+
+    {:img, attributes, children}
+  end
+
+  def scrub({:comment, _text, _children}), do: ""
+
+  def scrub({tag, attributes, children}), do: {tag, attributes, children}
+  def scrub({_tag, children}), do: children
+  def scrub(text), do: text
+end
diff --git a/priv/scrubbers/twitter_text.ex b/priv/scrubbers/twitter_text.ex
new file mode 100644
index 000000000..c4e796cad
--- /dev/null
+++ b/priv/scrubbers/twitter_text.ex
@@ -0,0 +1,57 @@
+defmodule Pleroma.HTML.Scrubber.TwitterText do
+  @moduledoc """
+  An HTML scrubbing policy which limits to twitter-style text.  Only
+  paragraphs, breaks and links are allowed through the filter.
+  """
+
+  @valid_schemes Pleroma.Config.get([:uri_schemes, :valid_schemes], [])
+
+  require FastSanitize.Sanitizer.Meta
+  alias FastSanitize.Sanitizer.Meta
+
+  Meta.strip_comments()
+
+  # links
+  Meta.allow_tag_with_uri_attributes(:a, ["href", "data-user", "data-tag"], @valid_schemes)
+
+  Meta.allow_tag_with_this_attribute_values(:a, "class", [
+    "hashtag",
+    "u-url",
+    "mention",
+    "u-url mention",
+    "mention u-url"
+  ])
+
+  Meta.allow_tag_with_this_attribute_values(:a, "rel", [
+    "tag",
+    "nofollow",
+    "noopener",
+    "noreferrer"
+  ])
+
+  Meta.allow_tag_with_these_attributes(:a, ["name", "title"])
+
+  # paragraphs and linebreaks
+  Meta.allow_tag_with_these_attributes(:br, [])
+  Meta.allow_tag_with_these_attributes(:p, [])
+
+  # microformats
+  Meta.allow_tag_with_this_attribute_values(:span, "class", ["h-card"])
+  Meta.allow_tag_with_these_attributes(:span, [])
+
+  # allow inline images for custom emoji
+  if Pleroma.Config.get([:markup, :allow_inline_images]) do
+    # restrict img tags to http/https only, because of MediaProxy.
+    Meta.allow_tag_with_uri_attributes(:img, ["src"], ["http", "https"])
+
+    Meta.allow_tag_with_these_attributes(:img, [
+      "width",
+      "height",
+      "class",
+      "title",
+      "alt"
+    ])
+  end
+
+  Meta.strip_everything_not_covered()
+end