1 files changed, 70 insertions, 0 deletions
diff --git a/app/finders/concerns/finder_with_cross_project_access.rb b/app/finders/concerns/finder_with_cross_project_access.rb
new file mode 100644
index 00000000000..92bf98d7cd2
--- /dev/null
+++ b/app/finders/concerns/finder_with_cross_project_access.rb
@@ -0,0 +1,70 @@
+# Module to prepend into finders to specify wether or not the finder requires
+# cross project access
+#
+# This module depends on the finder implementing the following methods:
+#
+# - `#execute` should return an `ActiveRecord::Relation`
+# - `#current_user` the user that requires access (or nil)
+module FinderWithCrossProjectAccess
+  extend ActiveSupport::Concern
+  extend ::Gitlab::Utils::Override
+
+  prepended do
+    extend Gitlab::CrossProjectAccess::ClassMethods
+  end
+
+  override :execute
+  def execute(*args)
+    check = Gitlab::CrossProjectAccess.find_check(self)
+    original = super
+
+    return original unless check
+    return original if should_skip_cross_project_check || can_read_cross_project?
+
+    if check.should_run?(self)
+      original.model.none
+    else
+      original
+    end
+  end
+
+  # We can skip the cross project check for finding indivitual records.
+  # this would be handled by the `can?(:read_*, result)` call in `FinderMethods`
+  # itself.
+  override :find_by!
+  def find_by!(*args)
+    skip_cross_project_check { super }
+  end
+
+  override :find_by
+  def find_by(*args)
+    skip_cross_project_check { super }
+  end
+
+  override :find
+  def find(*args)
+    skip_cross_project_check { super }
+  end
+
+  private
+
+  attr_accessor :should_skip_cross_project_check
+
+  def skip_cross_project_check
+    self.should_skip_cross_project_check = true
+
+    yield
+  ensure
+    # The find could raise an `ActiveRecord::RecordNotFound`, after which we
+    # still want to re-enable the check.
+    self.should_skip_cross_project_check = false
+  end
+
+  def can_read_cross_project?
+    Ability.allowed?(current_user, :read_cross_project)
+  end
+
+  def can_read_project?(project)
+    Ability.allowed?(current_user, :read_project, project)
+  end
+end