* lib/openssl/ssl.rb: Fix SSL client connection crash for SAN marked

critical.
  The patch for CVE-2013-4073 caused SSL crash when a SSL server returns
  the certificate that has critical SAN value.  X509 extension could
  include 2 or 3 elements in it:

  [id, criticality, octet_string] if critical,
  [id, octet_string] if not.

  Making sure to pick the last element of X509 extension and use it as
  SAN value.
  [ruby-core:55685] [Bug #8575]

  Thank you @nahi for providing the patch!


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41805 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,20 @@
+Sat Jul  6 06:06:16 2013  Martin Bosslet  <Martin.Bosslet@gmail.com>
+
+	* lib/openssl/ssl.rb: Fix SSL client connection crash for SAN marked
+	  critical.
+	  The patch for CVE-2013-4073 caused SSL crash when a SSL server returns
+	  the certificate that has critical SAN value.  X509 extension could
+	  include 2 or 3 elements in it:
+
+	  [id, criticality, octet_string] if critical,
+	  [id, octet_string] if not.
+
+	  Making sure to pick the last element of X509 extension and use it as
+	  SAN value.
+	  [ruby-core:55685] [Bug #8575]
+
+	  Thank you @nahi for providing the patch!
+
 Sat Jul  6 04:49:38 2013  Aaron Patterson <aaron@tenderlovemaking.com>
 
 	* ext/psych/lib/psych/visitors/yaml_tree.rb: register time objects so

ext/openssl/lib/openssl/ssl.rb

@@ -98,7 +98,7 @@ module OpenSSL
       should_verify_common_name = true
       cert.extensions.each{|ext|
         next if ext.oid != "subjectAltName"
-        id, ostr = OpenSSL::ASN1.decode(ext.to_der).value
+        ostr = OpenSSL::ASN1.decode(ext.to_der).value.last
         sequence = OpenSSL::ASN1.decode(ostr.value)
         sequence.value.each{|san|
           case san.tag

test/openssl/test_ssl.rb

@@ -338,25 +338,32 @@ class OpenSSL::TestSSL < OpenSSL::SSLTestCase
   end
 
   def test_verify_certificate_identity
-    # creating NULL byte SAN certificate
+    [true, false].each do |criticality|
+      cert = create_null_byte_SAN_certificate(criticality)
+      assert_equal(false, OpenSSL::SSL.verify_certificate_identity(cert, 'www.example.com'))
+      assert_equal(true,  OpenSSL::SSL.verify_certificate_identity(cert, 'www.example.com\0.evil.com'))
+      assert_equal(false, OpenSSL::SSL.verify_certificate_identity(cert, '192.168.7.255'))
+      assert_equal(true,  OpenSSL::SSL.verify_certificate_identity(cert, '192.168.7.1'))
+      assert_equal(false, OpenSSL::SSL.verify_certificate_identity(cert, '13::17'))
+      assert_equal(true,  OpenSSL::SSL.verify_certificate_identity(cert, '13:0:0:0:0:0:0:17'))
+    end
+  end
+
+  # Create NULL byte SAN certificate
+  def create_null_byte_SAN_certificate(critical = false)
     ef = OpenSSL::X509::ExtensionFactory.new
     cert = OpenSSL::X509::Certificate.new
     cert.subject = OpenSSL::X509::Name.parse "/DC=some/DC=site/CN=Some Site"
-    ext = ef.create_ext('subjectAltName', 'DNS:placeholder,IP:192.168.7.1,IP:13::17')
+    ext = ef.create_ext('subjectAltName', 'DNS:placeholder,IP:192.168.7.1,IP:13::17', critical)
     ext_asn1 = OpenSSL::ASN1.decode(ext.to_der)
     san_list_der = ext_asn1.value.reduce(nil) { |memo,val| val.tag == 4 ? val.value : memo }
     san_list_asn1 = OpenSSL::ASN1.decode(san_list_der)
     san_list_asn1.value[0].value = 'www.example.com\0.evil.com'
-    ext_asn1.value[1].value = san_list_asn1.to_der
+    pos = critical ? 2 : 1
+    ext_asn1.value[pos].value = san_list_asn1.to_der
     real_ext = OpenSSL::X509::Extension.new ext_asn1
     cert.add_extension(real_ext)
-
+    cert
-    assert_equal(false, OpenSSL::SSL.verify_certificate_identity(cert, 'www.example.com'))
-    assert_equal(true,  OpenSSL::SSL.verify_certificate_identity(cert, 'www.example.com\0.evil.com'))
-    assert_equal(false, OpenSSL::SSL.verify_certificate_identity(cert, '192.168.7.255'))
-    assert_equal(true,  OpenSSL::SSL.verify_certificate_identity(cert, '192.168.7.1'))
-    assert_equal(false, OpenSSL::SSL.verify_certificate_identity(cert, '13::17'))
-    assert_equal(true,  OpenSSL::SSL.verify_certificate_identity(cert, '13:0:0:0:0:0:0:17'))
   end
 
   def test_tlsext_hostname