Allow to turn off TCP window scale opt per route

Add and use no window scale bit in the features field.

Note that this is not the same as setting a window scale of 0
as would happen with window limit on route.

Signed-off-by: Gilad Ben-Yossef <gilad@codefidence.com>
Sigend-off-by: Ori Finkelman <ori@comsleep.com>
Sigend-off-by: Yony Amit <yony@comsleep.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 6097491aa9fc..393c56921dcb 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3739,7 +3739,8 @@ void tcp_parse_options(struct sk_buff *skb, struct tcp_options_received *opt_rx,
                                 break;
                         case TCPOPT_WINDOW:
                                 if (opsize == TCPOLEN_WINDOW && th->syn &&
-                                    !estab && sysctl_tcp_window_scaling) {
+                                    !estab && sysctl_tcp_window_scaling &&
+                                    !dst_feature(dst, RTAX_FEATURE_NO_WSCALE)) {
                                         __u8 snd_wscale = *(__u8 *)ptr;
                                         opt_rx->wscale_ok = 1;
                                         if (snd_wscale > 14) {