[CRIU] [PATCH] tcp: restore rcv_wscale in a repair mode

[Andrew Vagin]

rcv_wscale is a symetric parameter with snd_wscale.

Both this parameters are set on a connection handshake.

Without this valuea remote window size can't be interpreted correctly,
because a value from a packet should be shifted on rcv_wscale.

And one more thing is that we should set wscale_ok too.

This patch doesn't break a back compatibility, a rcv window
will be restored with the same bug (rcv_wscale = 0).

Signed-off-by: Andrew Vagin <avagin at 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 2109ff4..70d995c 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2325,10 +2325,22 @@ 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