Re: Protocol handler using dev_add_pack

[Eric Dumazet]

On Wed, 2012-07-11 at 10:38 -0300, Jerry Yu wrote:
> I am working on a kernel module to monitor all TCP packets. I created a protocol
> handler with protocol code ETH_P_ALL to handle all incoming and outgoing
> TCP packets. The code worked fine on 2.6.14 kernel, but in current 3.2.0-26
> kernel, I am no longer able to get the TCP payload for outgoing packets.
> The data in TCP payload section of skb->data are mainly 0x00. I am still
> able to get incoming TCP packets' payloads though.
> 
> Is there any change in 3.2.0 or other early kernel versions that will cause
> this issue?

Maybe you make wrong assumptions in your code.

skb->data doesnt exactly contains tcp payload of locally generated TCP
packets, unless you disabled scatter-gather on the NIC

ehtool -K eth0 sg off



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/