merge revision(s) 60149: [Backport #14003]

	Merge rubygems-2.6.14 changes.

	  It fixed http://blog.rubygems.org/2017/10/09/unsafe-object-deserialization-vulnerability.html

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_4@60168 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

5 files changed, 52 insertions, 4 deletions

diff --git a/lib/rubygems/config_file.rb b/lib/rubygems/config_file.rb
index c95d7dd1f1..63583b3616 100644
--- a/lib/rubygems/config_file.rb
+++ b/lib/rubygems/config_file.rb
@@ -345,7 +345,7 @@ if you believe they were disclosed to a third party.
     return {} unless filename and File.exist? filename
 
     begin
-      content = YAML.load(File.read(filename))
+      content = Gem::SafeYAML.load(File.read(filename))
       unless content.kind_of? Hash
         warn "Failed to load #{filename} because it doesn't contain valid YAML hash"
         return {}
diff --git a/lib/rubygems/package.rb b/lib/rubygems/package.rb
index c36e71d800..77811ed5ec 100644
--- a/lib/rubygems/package.rb
+++ b/lib/rubygems/package.rb
@@ -468,7 +468,7 @@ EOM
 
     @checksums = gem.seek 'checksums.yaml.gz' do |entry|
       Zlib::GzipReader.wrap entry do |gz_io|
-        YAML.load gz_io.read
+        Gem::SafeYAML.safe_load gz_io.read
       end
     end
   end
diff --git a/lib/rubygems/package/old.rb b/lib/rubygems/package/old.rb
index 5e722baa35..071f7141ab 100644
--- a/lib/rubygems/package/old.rb
+++ b/lib/rubygems/package/old.rb
@@ -101,7 +101,7 @@ class Gem::Package::Old < Gem::Package
       header << line
     end
 
-    YAML.load header
+    Gem::SafeYAML.safe_load header
   end
 
   ##
diff --git a/lib/rubygems/safe_yaml.rb b/lib/rubygems/safe_yaml.rb
new file mode 100644
index 0000000000..b98cfaa5e6
--- /dev/null
+++ b/lib/rubygems/safe_yaml.rb
@@ -0,0 +1,48 @@
+module Gem
+
+  ###
+  # This module is used for safely loading YAML specs from a gem.  The
+  # `safe_load` method defined on this module is specifically designed for
+  # loading Gem specifications.  For loading other YAML safely, please see
+  # Psych.safe_load
+
+  module SafeYAML
+    WHITELISTED_CLASSES = %w(
+      Symbol
+      Time
+      Date
+      Gem::Dependency
+      Gem::Platform
+      Gem::Requirement
+      Gem::Specification
+      Gem::Version
+      Gem::Version::Requirement
+      YAML::Syck::DefaultKey
+      Syck::DefaultKey
+    )
+
+    WHITELISTED_SYMBOLS = %w(
+      development
+      runtime
+    )
+
+    if ::YAML.respond_to? :safe_load
+      def self.safe_load input
+        ::YAML.safe_load(input, WHITELISTED_CLASSES, WHITELISTED_SYMBOLS, true)
+      end
+
+      def self.load input
+        ::YAML.safe_load(input, [::Symbol])
+      end
+    else
+      warn "YAML safe loading is not available. Please upgrade psych to a version that supports safe loading (>= 2.0)."
+      def self.safe_load input, *args
+        ::YAML.load input
+      end
+
+      def self.load input
+        ::YAML.load input
+      end
+    end
+  end
+end
diff --git a/lib/rubygems/specification.rb b/lib/rubygems/specification.rb
index 88e320c05a..40e3a70d47 100644
--- a/lib/rubygems/specification.rb
+++ b/lib/rubygems/specification.rb
@@ -1101,7 +1101,7 @@ class Gem::Specification < Gem::BasicSpecification
     Gem.load_yaml
 
     input = normalize_yaml_input input
-    spec = YAML.load input
+    spec = Gem::SafeYAML.safe_load input
 
     if spec && spec.class == FalseClass then
       raise Gem::EndOfYAMLException