Packet encryption based on gre key value with ip xfrm command

Hi, I am trying to encrypt Gre packet have specific key values in GRE header with following command ip xfrm policy add src 192.168.1.9 dst 192.168.1.5 proto gre key 3 dir in tmpl src 192.168.1.9 dst 192.168.1.5 proto esp reqid 16387 mode transport But it is not working. If I remove the "key 3" from above system encrypt all GRE packets. I tried with kernel version 3.18 and iproute2 version.2.4. I got iproute2 patch file having changes to support filtering based on keys but didn't find corresponding kernel patch. How to encrypt Packets based on GRE key value.? Regards Harsh Jain