Patchwork netfilter: don't do window scaling for a picked up connection

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Submitter Changli Gao
Date April 1, 2012, 3:04 p.m.
Message ID <1333292683-31414-1-git-send-email-xiaosuo@gmail.com>
Download mbox | patch
Permalink /patch/149929/
State Not Applicable
Delegated to: David Miller
Headers show

Comments

Changli Gao - April 1, 2012, 3:04 p.m.
For a picked up connection, the window scaling option is also lost, because this
option is only valid in SYN or SYN/ACK segments. We should remove the useless
expression to save the CPU power.

Signed-off-by: Changli Gao <xiaosuo@gmail.com>
---
 net/netfilter/nf_conntrack_proto_tcp.c |    1 -
 1 file changed, 1 deletion(-)
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Pablo Neira - April 1, 2012, 4:21 p.m.
On Sun, Apr 01, 2012 at 11:04:43PM +0800, Changli Gao wrote:
> For a picked up connection, the window scaling option is also lost, because this
> option is only valid in SYN or SYN/ACK segments. We should remove the useless
> expression to save the CPU power.
> 
> Signed-off-by: Changli Gao <xiaosuo@gmail.com>
> ---
>  net/netfilter/nf_conntrack_proto_tcp.c |    1 -
>  1 file changed, 1 deletion(-)
> diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
> index 361eade..22f0500 100644
> --- a/net/netfilter/nf_conntrack_proto_tcp.c
> +++ b/net/netfilter/nf_conntrack_proto_tcp.c
> @@ -584,7 +584,6 @@ static bool tcp_in_window(const struct nf_conn *ct,
>  			 * Let's try to use the data from the packet.
>  			 */
>  			sender->td_end = end;
> -			win <<= sender->td_scale;

This breaks conntrackd and its ability to recover flows by injecting
the window scaling via ctnetlink.
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Changli Gao - April 1, 2012, 4:41 p.m.
On Mon, Apr 2, 2012 at 12:21 AM, Pablo Neira Ayuso <pablo@netfilter.org> wrote:
>
> This breaks conntrackd and its ability to recover flows by injecting
> the window scaling via ctnetlink.

Got it. Thanks.

Just forget this patch. I'll post another patch to fix the duplicate
window scaling: one is here, and the other is before the state
updating code.

Patch

diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
index 361eade..22f0500 100644
--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -584,7 +584,6 @@  static bool tcp_in_window(const struct nf_conn *ct,
 			 * Let's try to use the data from the packet.
 			 */
 			sender->td_end = end;
-			win <<= sender->td_scale;
 			sender->td_maxwin = (win == 0 ? 1 : win);
 			sender->td_maxend = end + sender->td_maxwin;
 			/*