netdev - Re: [PATCHv2] netfilter: Remove skb_is_nonlinear check from nf_conntrack

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Date:	Fri, 14 May 2010 21:26:02 +0200
From:	Patrick McHardy <kaber@...sh.net>
To:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
CC:	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCHv2] netfilter: Remove skb_is_nonlinear check from	nf_conntrack_sip

Patrick McHardy wrote:
> Jason Gunthorpe wrote:
>> On Fri, May 14, 2010 at 08:13:03PM +0200, Patrick McHardy wrote:
>>> Your patch is based on an old version, the current version also
>>> supports TCP. I'll commit this patch to my tree after some testing.
>> Thanks!
>>
>>> diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
>>> index b20f427..45750cc 100644
>>> +++ b/net/netfilter/nf_conntrack_sip.c
>>> @@ -1393,10 +1393,8 @@ static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff,
>>>  
>>>  	nf_ct_refresh(ct, skb, sip_timeout * HZ);
>>>  
>>> -	if (skb_is_nonlinear(skb)) {
>>> -		pr_debug("Copy of skbuff not supported yet.\n");
>>> +	if (unlikely(skb_linearize(skb)))
>>>  		return NF_ACCEPT;
>>> -	}
>> Should this be NF_DROP? As I understand it skb_linearize only failes
>> if it runs out of memory, which probably means dropping is OK. But
>> passing a packet that might need rewriting could be harmful..
> 
> We so far also didn't rewrite the packet. But agreed, its
> a corner case and dropping it is the safer choice.

This is what I've added to my tree. Tested with asterisk and TSO
enabled NIC, which fails without this patch.

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