Merge pull request #300 from Shopify/cherry_pick_security_fix_to_2-6-stable

Cherry pick security fix to 2-6-stable

History.md

@@ -3,7 +3,13 @@
 IMPORTANT: Liquid 2.6 is going to be the last version of Liquid which maintains explicit Ruby 1.8 compatability.
 The following releases will only be tested against Ruby 1.9 and Ruby 2.0 and are likely to break on Ruby 1.8.
 
-## 2.6.0 / 2013-11-25 / branch "2.6-stable"
+## 2.6.1 / 2014-01-10 / branch "2-6-stable"
+
+Security fix, cherry-picked from master (4e14a65):
+* Don't call to_sym when creating conditions for security reasons, see #273 [Bouke van der Bijl, bouk]
+* Prevent arbitrary method invocation on condition objects, see #274 [Dylan Thacker-Smith, dylanahsmith]
+
+## 2.6.0 / 2013-11-25
 
 * ...
 * Bugfix for #106: fix example servlet [gnowoel]

lib/liquid/tags/if.rb

@@ -15,6 +15,7 @@ module Liquid
     SyntaxHelp = "Syntax Error in tag 'if' - Valid syntax: if [expression]"
     Syntax = /(#{QuotedFragment})\s*([=!<>a-z_]+)?\s*(#{QuotedFragment})?/o
     ExpressionsAndOperators = /(?:\b(?:\s?and\s?|\s?or\s?)\b|(?:\s*(?!\b(?:\s?and\s?|\s?or\s?)\b)(?:#{QuotedFragment}|\S+)\s*)+)/o
+    BOOLEAN_OPERATORS = %w(and or)
 
     def initialize(tag_name, markup, tokens)
       @blocks = []
@@ -61,7 +62,8 @@ module Liquid
             raise(SyntaxError, SyntaxHelp) unless expressions.shift.to_s =~ Syntax
 
             new_condition = Condition.new($1, $2, $3)
-            new_condition.send(operator.to_sym, condition)
+            raise SyntaxError, "invalid boolean operator" unless BOOLEAN_OPERATORS.include?(operator)
+            new_condition.send(operator, condition)
             condition = new_condition
           end
 
@@ -71,8 +73,6 @@ module Liquid
         @blocks.push(block)
         @nodelist = block.attach(Array.new)
       end
-
-
   end
 
   Template.register_tag('if', If)

test/liquid/tags/if_else_tag_test.rb

@@ -157,4 +157,10 @@ class IfElseTagTest < Test::Unit::TestCase
     assert_template_result('yes',
                            %({% if 'gnomeslab-and-or-liquid' contains 'gnomeslab-and-or-liquid' %}yes{% endif %}))
   end
+
+  def test_operators_are_whitelisted
+    assert_raise(SyntaxError) do
+      assert_template_result('', %({% if 1 or throw or or 1 %}yes{% endif %}))
+    end
+  end
 end # IfElseTest