* [PATCH] tcp: restore rcv_wscale in a repair mode
@ 2012-09-13 21:28 Andrew Vagin
2012-09-17 17:25 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: Andrew Vagin @ 2012-09-13 21:28 UTC (permalink / raw)
To: netdev
Cc: linux-kernel, Pavel Emelyanov, Andrew Vagin, David S. Miller,
Alexey Kuznetsov, James Morris, Hideaki YOSHIFUJI,
Patrick McHardy
rcv_wscale is a symetric parameter with snd_wscale.
Both this parameters are set on a connection handshake.
Without this value a remote window size can not be interpreted correctly,
because a value from a packet should be shifted on rcv_wscale.
And one more thing is that wscale_ok should be set too.
This patch doesn't break a backward compatibility.
If someone uses it in a old scheme, a rcv window
will be restored with the same bug (rcv_wscale = 0).
Cc: David S. Miller <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: James Morris <jmorris@namei.org>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Patrick McHardy <kaber@trash.net>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Vagin <avagin@openvz.org>
---
net/ipv4/tcp.c | 20 ++++++++++++++++----
1 files changed, 16 insertions(+), 4 deletions(-)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index df83d74..ed22cd7 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2348,10 +2348,22 @@ static int tcp_repair_options_est(struct tcp_sock *tp,
tp->rx_opt.mss_clamp = opt.opt_val;
break;
case TCPOPT_WINDOW:
- if (opt.opt_val > 14)
- return -EFBIG;
-
- tp->rx_opt.snd_wscale = opt.opt_val;
+ {
+ union {
+ struct {
+ u16 snd_wscale;
+ u16 rcv_wscale;
+ };
+ u32 raw;
+ } val = { .raw = opt.opt_val };
+
+ if (val.snd_wscale > 14 || val.rcv_wscale > 14)
+ return -EFBIG;
+
+ tp->rx_opt.snd_wscale = val.snd_wscale;
+ tp->rx_opt.rcv_wscale = val.rcv_wscale;
+ tp->rx_opt.wscale_ok = 1;
+ }
break;
case TCPOPT_SACK_PERM:
if (opt.opt_val != 0)
--
1.7.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] tcp: restore rcv_wscale in a repair mode
2012-09-13 21:28 [PATCH] tcp: restore rcv_wscale in a repair mode Andrew Vagin
@ 2012-09-17 17:25 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2012-09-17 17:25 UTC (permalink / raw)
To: avagin; +Cc: netdev, linux-kernel, xemul, kuznet, jmorris, yoshfuji, kaber
From: Andrew Vagin <avagin@openvz.org>
Date: Fri, 14 Sep 2012 01:28:07 +0400
> This patch doesn't break a backward compatibility.
> If someone uses it in a old scheme, a rcv window
> will be restored with the same bug (rcv_wscale = 0).
The whole world is not little-endian. This does in fact break
backwards compatability.
You will need to extend this in a more reasonable manner.
^ permalink raw reply [flat|nested] 2+ messages in thread
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