FEATURE: Secure uploads in PMs only (#23398)

This adds a new secure_uploads_pm_only site setting. When secure_uploads
is true with this setting, only uploads created in PMs will be marked
secure; no uploads in secure categories will be marked as secure, and
the login_required site setting has no bearing on upload security
either.

This is meant to be a stopgap solution to prevent secure uploads
in a single place (private messages) for sensitive admin data exports.
Ideally we would want a more comprehensive way of saying that certain
upload types get secured which is a hybrid/mixed mode secure uploads,
but for now this will do the trick.

spec/system/s3_secure_uploads_spec.rb

@@ -0,0 +1,118 @@
+# frozen_string_literal: true
+
+describe "Uploading files in the composer to S3", type: :system do
+  fab!(:current_user) { Fabricate(:admin) }
+  fab!(:other_user) { Fabricate(:user, username: "otherguy") }
+
+  let(:modal) { PageObjects::Modals::Base.new }
+  let(:composer) { PageObjects::Components::Composer.new }
+  let(:topic_page) { PageObjects::Pages::Topic.new }
+
+  describe "secure uploads" do
+    def first_post_img(wait: Capybara.default_max_wait_time)
+      first_post = topic_page.post_by_number(1, wait: wait)
+      expect(first_post).to have_css("img[data-base62-sha1]")
+      first_post.find(".cooked").first("img")
+    end
+
+    def expect_first_post_to_have_secure_upload
+      img = first_post_img
+      expect(img["src"]).to include("/secure-uploads")
+      topic = topic_page.current_topic
+      expect(topic.first_post.uploads.first.secure).to eq(true)
+    end
+
+    it "marks uploads inside of private message posts as secure" do
+      skip_unless_s3_system_specs_enabled!
+
+      setup_s3_system_test(enable_secure_uploads: true)
+      sign_in(current_user)
+
+      topic_page.open_new_message
+
+      composer.fill_title("This is a test PM for secure uploads")
+      composer.select_pm_user("otherguy")
+
+      file_path = file_from_fixtures("logo.png", "images").path
+      attach_file(file_path) { composer.click_toolbar_button("upload") }
+
+      expect(page).to have_no_css("#file-uploading")
+      expect(composer.preview).to have_css(".image-wrapper")
+
+      composer.submit
+
+      expect_first_post_to_have_secure_upload
+    end
+
+    it "marks uploads inside of private category posts as secure" do
+      skip_unless_s3_system_specs_enabled!
+
+      private_category = Fabricate(:private_category, group: Fabricate(:group))
+      setup_s3_system_test(enable_secure_uploads: true)
+      sign_in(current_user)
+
+      topic_page.open_new_topic
+
+      composer.fill_title("This is a test PM for secure uploads")
+      composer.switch_category(private_category.name)
+
+      file_path = file_from_fixtures("logo.png", "images").path
+      attach_file(file_path) { composer.click_toolbar_button("upload") }
+
+      expect(page).to have_no_css("#file-uploading")
+      expect(composer.preview).to have_css(".image-wrapper")
+
+      composer.submit
+
+      expect_first_post_to_have_secure_upload
+    end
+
+    it "marks uploads for all posts as secure when login_required" do
+      skip_unless_s3_system_specs_enabled!
+
+      SiteSetting.login_required = true
+      setup_s3_system_test(enable_secure_uploads: true)
+      sign_in(current_user)
+
+      topic_page.open_new_topic
+
+      composer.fill_title("This is a test PM for secure uploads")
+
+      file_path = file_from_fixtures("logo.png", "images").path
+      attach_file(file_path) { composer.click_toolbar_button("upload") }
+
+      expect(page).to have_no_css("#file-uploading")
+      expect(composer.preview).to have_css(".image-wrapper")
+
+      composer.submit
+
+      expect_first_post_to_have_secure_upload
+    end
+
+    it "doesn't mark uploads for public posts as secure" do
+      skip_unless_s3_system_specs_enabled!
+
+      setup_s3_system_test(enable_secure_uploads: true)
+      sign_in(current_user)
+
+      topic_page.open_new_topic
+
+      composer.fill_title("This is a test PM for secure uploads")
+
+      file_path = file_from_fixtures("logo.png", "images").path
+      attach_file(file_path) { composer.click_toolbar_button("upload") }
+
+      expect(page).to have_no_css("#file-uploading")
+      expect(composer.preview).to have_css(".image-wrapper")
+
+      Jobs.run_immediately!
+      composer.submit
+
+      # Extra wait time is added because the job can slow down the processing of the request.
+      img = first_post_img(wait: 10)
+      expect(img["src"]).not_to include("/secure-uploads")
+      topic = topic_page.current_topic
+      expect(topic.first_post.uploads.first.secure).to eq(false)
+    end
+  end
+end