CVE-2013-0156: Safe XML params parsing. Doesn't allow symbols or yaml.

actionpack/test/controller/webservice_test.rb

@@ -118,6 +118,19 @@ def test_post_xml_using_an_attributted_node_named_type
     end
   end
 
+  def test_post_xml_using_a_disallowed_type_attribute
+    $stderr = StringIO.new
+    with_test_route_set do
+      post '/', '<foo type="symbol">value</foo>', 'CONTENT_TYPE' => 'application/xml'
+      assert_response 500
+
+      post '/', '<foo type="yaml">value</foo>', 'CONTENT_TYPE' => 'application/xml'
+      assert_response 500
+    end
+  ensure
+    $stderr = STDERR
+  end
+
   def test_register_and_use_yaml
     with_test_route_set do
       with_params_parsers Mime::YAML => Proc.new { |d| YAML.load(d) } do

activesupport/CHANGELOG.md

@@ -1,3 +1,12 @@
+## Rails 3.1.10 (Jan 8, 2012) ##
+
+*   Hash.from_xml raises when it encounters type="symbol" or type="yaml".
+    Use Hash.from_trusted_xml to parse this XML.
+
+    CVE-2013-0156
+
+    *Jeremy Kemper*
+
 ## Rails 3.1.9
 
 ## Rails 3.1.8 (Aug 9, 2012)

activesupport/lib/active_support/core_ext/hash/conversions.rb

@@ -85,25 +85,43 @@ def to_xml(options = {})
     end
   end
 
+  class DisallowedType < StandardError #:nodoc:
+    def initialize(type)
+      super "Disallowed type attribute: #{type.inspect}"
+    end
+  end
+
+  DISALLOWED_XML_TYPES = %w(symbol yaml)
+
   class << self
-    def from_xml(xml)
-      typecast_xml_value(unrename_keys(ActiveSupport::XmlMini.parse(xml)))
+    def from_xml(xml, disallowed_types = nil)
+      typecast_xml_value(unrename_keys(ActiveSupport::XmlMini.parse(xml)), disallowed_types)
+    end
+
+    def from_trusted_xml(xml)
+      from_xml xml, []
     end
 
     private
-      def typecast_xml_value(value)
+      def typecast_xml_value(value, disallowed_types = nil)
+        disallowed_types ||= DISALLOWED_XML_TYPES
+
         case value.class.to_s
           when 'Hash'
+            if value.include?('type') && !value['type'].is_a?(Hash) && disallowed_types.include?(value['type'])
+              raise DisallowedType, value['type']
+            end
+
             if value['type'] == 'array'
               _, entries = Array.wrap(value.detect { |k,v| not v.is_a?(String) })
               if entries.nil? || (c = value['__content__'] && c.blank?)
                 []
               else
                 case entries.class.to_s   # something weird with classes not matching here.  maybe singleton methods breaking is_a?
                 when "Array"
-                  entries.collect { |v| typecast_xml_value(v) }
+                  entries.collect { |v| typecast_xml_value(v, disallowed_types) }
                 when "Hash"
-                  [typecast_xml_value(entries)]
+                  [typecast_xml_value(entries, disallowed_types)]
                 else
                   raise "can't typecast #{entries.inspect}"
                 end
@@ -127,14 +145,14 @@ def typecast_xml_value(value)
             elsif value['type'] && value.size == 1 && !value['type'].is_a?(::Hash)
               nil
             else
-              xml_value = Hash[value.map { |k,v| [k, typecast_xml_value(v)] }]
+              xml_value = Hash[value.map { |k,v| [k, typecast_xml_value(v, disallowed_types)] }]
 
               # Turn { :files => { :file => #<StringIO> } into { :files => #<StringIO> } so it is compatible with
               # how multipart uploaded files from HTML appear
               xml_value["file"].is_a?(StringIO) ? xml_value["file"] : xml_value
             end
           when 'Array'
-            value.map! { |i| typecast_xml_value(i) }
+            value.map! { |i| typecast_xml_value(i, disallowed_types) }
             value.length > 1 ? value : value.first
           when 'String'
             value

activesupport/test/core_ext/hash_ext_test.rb

@@ -730,12 +730,10 @@ def test_single_record_from_xml
         <replies-close-in type="integer">2592000000</replies-close-in>
         <written-on type="date">2003-07-16</written-on>
         <viewed-at type="datetime">2003-07-16T09:28:00+0000</viewed-at>
-        <content type="yaml">--- \n1: should be an integer\n:message: Have a nice day\narray: \n- should-have-dashes: true\n  should_have_underscores: true\n</content>
         <author-email-address>david@loudthinking.com</author-email-address>
         <parent-id></parent-id>
         <ad-revenue type="decimal">1.5</ad-revenue>
         <optimum-viewing-angle type="float">135</optimum-viewing-angle>
-        <resident type="symbol">yes</resident>
       </topic>
     EOT
 
@@ -748,12 +746,10 @@ def test_single_record_from_xml
       :replies_close_in => 2592000000,
       :written_on => Date.new(2003, 7, 16),
       :viewed_at => Time.utc(2003, 7, 16, 9, 28),
-      :content => { :message => "Have a nice day", 1 => "should be an integer", "array" => [{ "should-have-dashes" => true, "should_have_underscores" => true }] },
       :author_email_address => "david@loudthinking.com",
       :parent_id => nil,
       :ad_revenue => BigDecimal("1.50"),
       :optimum_viewing_angle => 135.0,
-      :resident => :yes
     }.stringify_keys
 
     assert_equal expected_topic_hash, Hash.from_xml(topic_xml)["topic"]
@@ -767,7 +763,6 @@ def test_single_record_from_xml_with_nil_values
         <approved type="boolean"></approved>
         <written-on type="date"></written-on>
         <viewed-at type="datetime"></viewed-at>
-        <content type="yaml"></content>
         <parent-id></parent-id>
       </topic>
     EOT
@@ -778,7 +773,6 @@ def test_single_record_from_xml_with_nil_values
       :approved   => nil,
       :written_on => nil,
       :viewed_at  => nil,
-      :content    => nil,
       :parent_id  => nil
     }.stringify_keys
 
@@ -1005,6 +999,28 @@ def test_type_trickles_through_when_unknown
     assert_equal expected_product_hash, Hash.from_xml(product_xml)["product"]
   end
 
+  def test_from_xml_raises_on_disallowed_type_attributes
+    assert_raise Hash::DisallowedType do
+      Hash.from_xml '<product><name type="foo">value</name></product>', %w(foo)
+    end
+  end
+
+  def test_from_xml_disallows_symbol_and_yaml_types_by_default
+    assert_raise Hash::DisallowedType do
+      Hash.from_xml '<product><name type="symbol">value</name></product>'
+    end
+
+    assert_raise Hash::DisallowedType do
+      Hash.from_xml '<product><name type="yaml">value</name></product>'
+    end
+  end
+
+  def test_from_trusted_xml_allows_symbol_and_yaml_types
+    expected = { 'product' => { 'name' => :value }}
+    assert_equal expected, Hash.from_trusted_xml('<product><name type="symbol">value</name></product>')
+    assert_equal expected, Hash.from_trusted_xml('<product><name type="yaml">:value</name></product>')
+  end
+
   def test_should_use_default_value_for_unknown_key
     hash_wia = HashWithIndifferentAccess.new(3)
     assert_equal 3, hash_wia[:new_key]