[001/001] QoS and/or fair queueing: Stateless NAT BUG

Hi all,
I have been testing Stateless NAT and found that ICMP packets with length
less than 20 bytes were not correctly NAT'ed. I have found a BUG that
makes taking into account IP header length twice, so ICMP packets smaller
than 20 bytes were being dropped.

Proposed formal patch is below, as suggested by Eric Dumazet, thanks.
It is taken from 2.6.34.1 stable version.

Signed-off-by: Rodrigo Partearroyo González <rpartearroyo@albentia.com>
---
---
Rodrigo Partearroyo González
R&D Engineer

Albentia Systems S.A.
http://www.albentia.com
+34 914400213

C\Margarita Salas 22
Parque Tecnológico de Leganés
Leganés (28918)
Madrid
Spain
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From: Rodrigo Partearroyo González <rpartearroyo@albentia.com>
Date: Fri, 9 Jul 2010 19:37:16 +0200

> Hi all,
> I have been testing Stateless NAT and found that ICMP packets with length
> less than 20 bytes were not correctly NAT'ed. I have found a BUG that
> makes taking into account IP header length twice, so ICMP packets smaller
> than 20 bytes were being dropped.
> 
> Proposed formal patch is below, as suggested by Eric Dumazet, thanks.
> It is taken from 2.6.34.1 stable version.
> 
> Signed-off-by: Rodrigo Partearroyo González <rpartearroyo@albentia.com>

Applied, thanks.
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Le vendredi 09 juillet 2010 à 19:37 +0200, Rodrigo Partearroyo González
a écrit :
> Hi all,
> I have been testing Stateless NAT and found that ICMP packets with length
> less than 20 bytes were not correctly NAT'ed. I have found a BUG that
> makes taking into account IP header length twice, so ICMP packets smaller
> than 20 bytes were being dropped.
> 
> Proposed formal patch is below, as suggested by Eric Dumazet, thanks.
> It is taken from 2.6.34.1 stable version.
> 
> Signed-off-by: Rodrigo Partearroyo González <rpartearroyo@albentia.com>

Acked-by: Eric Dumazet <eric.dumazet@gmail.com>

> ---
> diff -uprN a/net/sched/act_nat.c b/net/sched/act_nat.c
> --- a/net/sched/act_nat.c	2010-07-09 18:25:18.000000000 +0200
> +++ b/net/sched/act_nat.c	2010-07-09 18:26:16.000000000 +0200
> @@ -202,7 +202,7 @@ static int tcf_nat(struct sk_buff *skb, 
>  	{
>  		struct icmphdr *icmph;
>  
> -		if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph)))
> +		if (!pskb_may_pull(skb, ihl + sizeof(*icmph)))
>  			goto drop;
>  
>  		icmph = (void *)(skb_network_header(skb) + ihl);
> @@ -223,7 +223,7 @@ static int tcf_nat(struct sk_buff *skb, 
>  
>  		if (skb_cloned(skb) &&
>  		    !skb_clone_writable(skb,
> -					ihl + sizeof(*icmph) + sizeof(*iph)) &&
> +					ihl + sizeof(*icmph)) &&
>  		    pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
>  			goto drop;
> 




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