Allow disabling of DSACK TCP option per route

Add and use no DSCAK 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>

2 files changed, 7 insertions, 2 deletions

diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index 6784b342cbbf..e78b60cd65a4 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -381,6 +381,7 @@ enum
 #define RTAX_FEATURE_NO_TSTAMP  0x00000004
 #define RTAX_FEATURE_ALLFRAG    0x00000008
 #define RTAX_FEATURE_NO_WSCALE  0x00000010
+#define RTAX_FEATURE_NO_DSACK   0x00000020
 
 struct rta_session
 {
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 393c56921dcb..ba0eab65fe80 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4080,8 +4080,10 @@ static inline int tcp_sack_extend(struct tcp_sack_block *sp, u32 seq,
 static void tcp_dsack_set(struct sock *sk, u32 seq, u32 end_seq)
 {
         struct tcp_sock *tp = tcp_sk(sk);
+        struct dst_entry *dst = __sk_dst_get(sk);
 
-        if (tcp_is_sack(tp) && sysctl_tcp_dsack) {
+        if (tcp_is_sack(tp) && sysctl_tcp_dsack &&
+            !dst_feature(dst, RTAX_FEATURE_NO_DSACK)) {
                 int mib_idx;
 
                 if (before(seq, tp->rcv_nxt))
@@ -4110,13 +4112,15 @@ static void tcp_dsack_extend(struct sock *sk, u32 seq, u32 end_seq)
 static void tcp_send_dupack(struct sock *sk, struct sk_buff *skb)
 {
         struct tcp_sock *tp = tcp_sk(sk);
+        struct dst_entry *dst = __sk_dst_get(sk);
 
         if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq &&
             before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) {
                 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKLOST);
                 tcp_enter_quickack_mode(sk);
 
-                if (tcp_is_sack(tp) && sysctl_tcp_dsack) {
+                if (tcp_is_sack(tp) && sysctl_tcp_dsack &&
+                    !dst_feature(dst, RTAX_FEATURE_NO_DSACK)) {
                         u32 end_seq = TCP_SKB_CB(skb)->end_seq;
 
                         if (after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt))