From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Vagin Subject: [PATCH] tcp: restore rcv_wscale in a repair mode (v2) Date: Wed, 19 Sep 2012 23:40:00 +0400 Message-ID: <1348083600-3881500-1-git-send-email-avagin@openvz.org> Cc: linux-kernel@vger.kernel.org, Andrew Vagin , "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , Pavel Emelyanov To: netdev@vger.kernel.org Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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). v2: Save backward compatibility on big-endian system. Before the first two bytes were snd_wscale and the second two bytes were rcv_wscale. Now snd_wscale is opt_val & 0xFFFF and rcv_wscale >> 16. This approach is independent on byte ordering. Cc: David S. Miller Cc: Alexey Kuznetsov Cc: James Morris Cc: Hideaki YOSHIFUJI Cc: Patrick McHardy CC: Pavel Emelyanov Signed-off-by: Andrew Vagin --- net/ipv4/tcp.c | 13 ++++++++++--- 1 files changed, 10 insertions(+), 3 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index df83d74..42689aa 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2348,10 +2348,17 @@ 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; + { + u16 snd_wscale = opt.opt_val & 0xFFFF; + u16 rcv_wscale = opt.opt_val >> 16; + + if (snd_wscale > 14 || rcv_wscale > 14) + return -EFBIG; - tp->rx_opt.snd_wscale = opt.opt_val; + tp->rx_opt.snd_wscale = snd_wscale; + tp->rx_opt.rcv_wscale = rcv_wscale; + tp->rx_opt.wscale_ok = 1; + } break; case TCPOPT_SACK_PERM: if (opt.opt_val != 0) -- 1.7.1