Re: PATCH: "invalid SYNIN=" - a patch and a question

[Patrick McHardy <kaber@trash.net>]

Jozsef Kadlecsik wrote:
> Hi Patrick,
> 
> On Thu, 4 Oct 2007, Patrick McHardy wrote:
> 
>>Jozsef Kadlecsik wrote:
>>
>>>I think the code segment is correct. However, the end of the segment 
>>>is miscalculated by segment_seq_plus_len because the offset added to 
>>>'dataoff' by the get_l4proto function of IPv4/IPv6 is not taken into 
>>>account. Please check whether the patch below fixes it:
>>
>>Actually that offset should always be zero for anything but packets
>>encapsulated within ICMP, which don't pass though TCP conntrack.
> 
> 
> Here we calculate the sequence number of the last octet in the packet from 
> the actual data length of the skbuff, so by the 'dataoff' argument of 
> segment_seq_plus_len we must pass the length of the IP(v4|6) header. But 
> the 'dataoff' parameter supplied by the nf_conntrack core is larger by 
> skb_network_offset(skb) therefore 'dataoff' must be decremented by it 
> before passing to segment_seq_plus_len.


Right, I didn't express myself correctly. What I meant to say is that
skb_network_offset is always 0 while we're inside the IP(v6) layer.