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>

diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index adf2068..9c802a6 100644 (file)
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -377,7 +377,7 @@ enum
 #define RTAX_MAX (__RTAX_MAX - 1)
 
 #define RTAX_FEATURE_ECN       0x00000001
-#define RTAX_FEATURE_SACK      0x00000002
+#define RTAX_FEATURE_NO_SACK   0x00000002
 #define RTAX_FEATURE_TIMESTAMP 0x00000004
 #define RTAX_FEATURE_ALLFRAG   0x00000008
 

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index c762500..5fb25f9 100644 (file)
--- 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);
                                }

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 2e2eb74..b35802a 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -464,6 +464,7 @@ static unsigned tcp_syn_options(struct sock *sk, struct sk_buff *skb,
                                struct tcp_md5sig_key **md5) {
        struct tcp_sock *tp = tcp_sk(sk);
        unsigned size = 0;
+       struct dst_entry *dst = __sk_dst_get(sk);
 
 #ifdef CONFIG_TCP_MD5SIG
        *md5 = tp->af_specific->md5_lookup(sk, sk);
@@ -498,7 +499,8 @@ static unsigned tcp_syn_options(struct sock *sk, struct sk_buff *skb,
                opts->options |= OPTION_WSCALE;
                size += TCPOLEN_WSCALE_ALIGNED;
        }
-       if (likely(sysctl_tcp_sack)) {
+       if (likely(sysctl_tcp_sack &&
+                  !dst_feature(dst, RTAX_FEATURE_NO_SACK))) {
                opts->options |= OPTION_SACK_ADVERTISE;
                if (unlikely(!(OPTION_TS & opts->options)))
                        size += TCPOLEN_SACKPERM_ALIGNED;