Subject: Re: [PATCH V4 7/7] ipvs: SIP fragment handling

From: Simon Horman <[email-masked]>
Date: Fri, 28 Sep 2012 11:43:58 +0900

On Wed, Sep 26, 2012 at 02:07:33PM +0200, Jesper Dangaard Brouer wrote:
> Use the nfct_reasm SKB if available.
> 
> Based on part of a patch from: Hans Schillstrom
> I have left Hans'es comment in the patch (marked /HS)
> 
> Signed-off-by: Jesper Dangaard Brouer <[email-masked]>
> 
> ---
> V3:
>  - I have split out the SIP fragment handling into a seperate patch.
>    As I have not been able to test this part.
>  - Change the strange SKB swapping reasm = skb, reverse logic to minimize patch
> 
> 
>  net/netfilter/ipvs/ip_vs_pe_sip.c |   19 +++++++++++++++----
>  1 files changed, 15 insertions(+), 4 deletions(-)

I realise that the commenting style used inside net/netfilter/ipvs/ is
wildly inconsistent, but I think it is worth using the preffered
style for network code where possible.

I intend to include the follwowing changes in my tree.

> 
> diff --git a/net/netfilter/ipvs/ip_vs_pe_sip.c b/net/netfilter/ipvs/ip_vs_pe_sip.c
> index ee4e2e3..43acba6 100644
> --- a/net/netfilter/ipvs/ip_vs_pe_sip.c
> +++ b/net/netfilter/ipvs/ip_vs_pe_sip.c
> @@ -68,6 +68,7 @@ static int get_callid(const char *dptr, unsigned int dataoff,
>  static int
>  ip_vs_sip_fill_param(struct ip_vs_conn_param *p, struct sk_buff *skb)
>  {
> +	struct sk_buff *reasm = skb_nfct_reasm(skb);
>  	struct ip_vs_iphdr iph;
>  	unsigned int dataoff, datalen, matchoff, matchlen;
>  	const char *dptr;
> @@ -78,13 +79,23 @@ ip_vs_sip_fill_param(struct ip_vs_conn_param *p, struct sk_buff *skb)
>  	/* Only useful with UDP */
>  	if (iph.protocol != IPPROTO_UDP)
>  		return -EINVAL;
> +	/*
> +	 * todo: IPv6 fragments:
> +	 *       I think this only should be done for the first fragment. /HS
> +	 */

	/* todo: IPv6 fragments:
	 *       I think this only should be done for the first fragment. /HS
	 */

> +	if (reasm) {
> +		skb = reasm;
> +		dataoff = iph.thoff_reasm + sizeof(struct udphdr);
> +	} else
> +		dataoff = iph.len + sizeof(struct udphdr);
>  
> -	/* No Data ? */
> -	dataoff = iph.len + sizeof(struct udphdr);
>  	if (dataoff >= skb->len)
>  		return -EINVAL;
> -
> -	if ((retc=skb_linearize(skb)) < 0)
> +	/*
> +	 * todo: Check if this will mess-up the reasm skb !!! /HS
> +	 */

	/* todo: Check if this will mess-up the reasm skb !!! /HS */

> +	retc = skb_linearize(skb);
> +	if (retc < 0)
>  		return retc;
>  	dptr = skb->data + dataoff;
>  	datalen = skb->len - dataoff;
>