Patchwork netfilter: don't scale the size of the window up twice

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Submitter Changli Gao
Date April 2, 2012, 3:25 a.m.
Message ID <1333337106-8279-1-git-send-email-xiaosuo@gmail.com>
Download mbox | patch
Permalink /patch/150057/
State Not Applicable
Delegated to: David Miller
Headers show

Comments

Changli Gao - April 2, 2012, 3:25 a.m.
For a picked up connection, the window win is scaled twice: one is by the
initialization code, and the other is by the sender updating code.

I use the temporary variable swin instead of modifying the variable win.

Signed-off-by: Changli Gao <xiaosuo@gmail.com>
---
 net/netfilter/nf_conntrack_proto_tcp.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
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Pablo Neira - April 4, 2012, 3:08 p.m.
On Mon, Apr 02, 2012 at 11:25:06AM +0800, Changli Gao wrote:
> For a picked up connection, the window win is scaled twice: one is by the
> initialization code, and the other is by the sender updating code.
> 
> I use the temporary variable swin instead of modifying the variable win.
> 
> Signed-off-by: Changli Gao <xiaosuo@gmail.com>
> ---
>  net/netfilter/nf_conntrack_proto_tcp.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
> index 361eade..0d07a1d 100644
> --- a/net/netfilter/nf_conntrack_proto_tcp.c
> +++ b/net/netfilter/nf_conntrack_proto_tcp.c
> @@ -584,8 +584,8 @@ 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);
> +			swin = win << sender->td_scale;
> +			sender->td_maxwin = (swin == 0 ? 1 : swin);
>  			sender->td_maxend = end + sender->td_maxwin;
>  			/*
>  			 * We haven't seen traffic in the other direction yet

Jozsef, do you remember if this is intentional?

I'm going to test this patch in my testbed to make sure this does not
break conntrackd.
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Jozsef Kadlecsik - April 4, 2012, 7:05 p.m.
On Wed, 4 Apr 2012, Pablo Neira Ayuso wrote:

> On Mon, Apr 02, 2012 at 11:25:06AM +0800, Changli Gao wrote:
> > For a picked up connection, the window win is scaled twice: one is by the
> > initialization code, and the other is by the sender updating code.
> > 
> > I use the temporary variable swin instead of modifying the variable win.
> > 
> > Signed-off-by: Changli Gao <xiaosuo@gmail.com>
> > ---
> >  net/netfilter/nf_conntrack_proto_tcp.c |    4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
> > index 361eade..0d07a1d 100644
> > --- a/net/netfilter/nf_conntrack_proto_tcp.c
> > +++ b/net/netfilter/nf_conntrack_proto_tcp.c
> > @@ -584,8 +584,8 @@ 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);
> > +			swin = win << sender->td_scale;
> > +			sender->td_maxwin = (swin == 0 ? 1 : swin);
> >  			sender->td_maxend = end + sender->td_maxwin;
> >  			/*
> >  			 * We haven't seen traffic in the other direction yet
> 
> Jozsef, do you remember if this is intentional?

No, it's a good spotting.

Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>

> I'm going to test this patch in my testbed to make sure this does not
> break conntrackd.

A checking in a testbed doesn't hurt :-).

Best regards,
Jozsef
-
E-mail  : kadlec@blackhole.kfki.hu, kadlecsik.jozsef@wigner.mta.hu
PGP key : http://www.kfki.hu/~kadlec/pgp_public_key.txt
Address : Wigner Research Centre for Physics, Hungarian Academy of Sciences
          H-1525 Budapest 114, POB. 49, Hungary
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Pablo Neira - April 10, 2012, 12:35 p.m.
On Wed, Apr 04, 2012 at 09:05:26PM +0200, Jozsef Kadlecsik wrote:
> On Wed, 4 Apr 2012, Pablo Neira Ayuso wrote:
> 
> > On Mon, Apr 02, 2012 at 11:25:06AM +0800, Changli Gao wrote:
> > > For a picked up connection, the window win is scaled twice: one is by the
> > > initialization code, and the other is by the sender updating code.
> > > 
> > > I use the temporary variable swin instead of modifying the variable win.
> > > 
> > > Signed-off-by: Changli Gao <xiaosuo@gmail.com>
> > > ---
> > >  net/netfilter/nf_conntrack_proto_tcp.c |    4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
> > > index 361eade..0d07a1d 100644
> > > --- a/net/netfilter/nf_conntrack_proto_tcp.c
> > > +++ b/net/netfilter/nf_conntrack_proto_tcp.c
> > > @@ -584,8 +584,8 @@ 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);
> > > +			swin = win << sender->td_scale;
> > > +			sender->td_maxwin = (swin == 0 ? 1 : swin);
> > >  			sender->td_maxend = end + sender->td_maxwin;
> > >  			/*
> > >  			 * We haven't seen traffic in the other direction yet
> > 
> > Jozsef, do you remember if this is intentional?
> 
> No, it's a good spotting.
> 
> Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>

Applied, thanks.
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Patch

diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
index 361eade..0d07a1d 100644
--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -584,8 +584,8 @@  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);
+			swin = win << sender->td_scale;
+			sender->td_maxwin = (swin == 0 ? 1 : swin);
 			sender->td_maxend = end + sender->td_maxwin;
 			/*
 			 * We haven't seen traffic in the other direction yet