FileHandler should not be called for files outside the root

FileHandler#matches? should return false for files that are outside the
"root" path.

Conflicts:
	actionpack/lib/action_dispatch/middleware/static.rb

Conflicts:
	actionpack/lib/action_dispatch/middleware/static.rb
	actionpack/test/dispatch/static_test.rb

2 files changed, 38 insertions, 1 deletions

diff --git a/actionpack/lib/action_dispatch/middleware/static.rb b/actionpack/lib/action_dispatch/middleware/static.rb
index a8d176560c..7f1117009d 100644
--- a/actionpack/lib/action_dispatch/middleware/static.rb
+++ b/actionpack/lib/action_dispatch/middleware/static.rb
@@ -12,7 +12,7 @@ module ActionDispatch
     def match?(path)
       path = path.dup
 
-      full_path = path.empty? ? @root : File.join(@root, escape_glob_chars(unescape_path(path)))
+      full_path = path.empty? ? @root : File.join(@root, escape_glob_chars(clean_path_info(unescape_path(path))))
       paths = "#{full_path}#{ext}"
 
       matches = Dir[paths]
@@ -42,6 +42,25 @@ module ActionDispatch
       path.force_encoding('binary') if path.respond_to? :force_encoding
       path.gsub(/[*?{}\[\]]/, "\\\\\\&")
     end
+
+    private
+
+    PATH_SEPS = Regexp.union(*[::File::SEPARATOR, ::File::ALT_SEPARATOR].compact)
+
+    def clean_path_info(path_info)
+      parts = path_info.split PATH_SEPS
+
+      clean = []
+
+      parts.each do |part|
+        next if part.empty? || part == '.'
+        part == '..' ? clean.pop : clean << part
+      end
+
+      clean.unshift '/' if parts.empty? || parts.first.empty?
+
+      ::File.join(*clean)
+    end
   end
 
   class Static
diff --git a/actionpack/test/dispatch/static_test.rb b/actionpack/test/dispatch/static_test.rb
index 856746c451..a035abdf08 100644
--- a/actionpack/test/dispatch/static_test.rb
+++ b/actionpack/test/dispatch/static_test.rb
@@ -140,10 +140,28 @@ class StaticTest < ActiveSupport::TestCase
     [200, {"Content-Type" => "text/plain"}, ["Hello, World!"]]
   }
   App = ActionDispatch::Static.new(DummyApp, "#{FIXTURE_LOAD_PATH}/public", "public, max-age=60")
+  Root = "#{FIXTURE_LOAD_PATH}/public"
 
   def setup
     @app = App
+    @root = Root
   end
 
   include StaticTests
+
+  def test_custom_handler_called_when_file_is_outside_root
+    filename = 'shared.html.erb'
+    assert File.exist?(File.join(@root, '..', filename))
+    env = {
+      "REQUEST_METHOD"=>"GET",
+      "REQUEST_PATH"=>"/..%2F#{filename}",
+      "PATH_INFO"=>"/..%2F#{filename}",
+      "REQUEST_URI"=>"/..%2F#{filename}",
+      "HTTP_VERSION"=>"HTTP/1.1",
+      "SERVER_NAME"=>"localhost",
+      "SERVER_PORT"=>"8080",
+      "QUERY_STRING"=>""
+    }
+    assert_equal(DummyApp.call(nil), @app.call(env))
+  end
 end