Add the no SACK route option feature

Implement querying and acting upon the no sack bit in the features
field.

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 c7625005486d..5fb25f977451 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3763,7 +3763,8 @@ void tcp_parse_options(struct sk_buff *skb, struct tcp_options_received *opt_rx,
                                 break;
                         case TCPOPT_SACK_PERM:
                                 if (opsize == TCPOLEN_SACK_PERM && th->syn &&
-                                    !estab && sysctl_tcp_sack) {
+                                    !estab && sysctl_tcp_sack &&
+                                    !dst_feature(dst, RTAX_FEATURE_NO_SACK)) {
                                         opt_rx->sack_ok = 1;
                                         tcp_sack_reset(opt_rx);
                                 }