Networking :: NETFILTER And Extraction Of Data From Non Linear Area Of Skbuff

i am writing a netfilter module for linux 2.6.34.6-47 / 2.6.35. while i could capture the packets on the incoming hook since the same came as a single packet in probably the allocated skbuff area by the stack, i found that packets going out of the machine are getting splitted into linear and non-linear area. skb->data gives the total length of packet as correct, but when i extract skb-> data to print it, it prints only ip and tcp header. Now to treat the data i need to extract it and then push it back on the route.

To clarify if my data is 3 bytes . the total length by passing pointers show as 55 bytes = ( 52 byte of header + 3 byte of data), but i can't access these 3 bytes by using skb->tail - skb->data. how to extract outgoing data for any further action and then put it back on route for further encapsulation by the L2 stack or whatever. will skb_linearize() or skb_linearize_cow() be of any use , if yes how and why?