Allow disabling TCP timestamp options per route

Implement querying and acting upon the no timestamp bit in the feature
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, 8 insertions, 3 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 5fb25f977451..6097491aa9fc 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3755,7 +3755,8 @@ void tcp_parse_options(struct sk_buff *skb, struct tcp_options_received *opt_rx,
                         case TCPOPT_TIMESTAMP:
                                 if ((opsize == TCPOLEN_TIMESTAMP) &&
                                     ((estab && opt_rx->tstamp_ok) ||
-                                     (!estab && sysctl_tcp_timestamps))) {
+                                     (!estab && sysctl_tcp_timestamps &&
+                                      !dst_feature(dst, RTAX_FEATURE_NO_TSTAMP)))) {
                                         opt_rx->saw_tstamp = 1;
                                         opt_rx->rcv_tsval = get_unaligned_be32(ptr);
                                         opt_rx->rcv_tsecr = get_unaligned_be32(ptr + 4);
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index b35802af3c4c..8819eba8ebb8 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -488,7 +488,9 @@ static unsigned tcp_syn_options(struct sock *sk, struct sk_buff *skb,
         opts->mss = tcp_advertise_mss(sk);
         size += TCPOLEN_MSS_ALIGNED;
 
-        if (likely(sysctl_tcp_timestamps && *md5 == NULL)) {
+        if (likely(sysctl_tcp_timestamps &&
+                   !dst_feature(dst, RTAX_FEATURE_NO_TSTAMP) &&
+                   *md5 == NULL)) {
                 opts->options |= OPTION_TS;
                 opts->tsval = TCP_SKB_CB(skb)->when;
                 opts->tsecr = tp->rx_opt.ts_recent;
@@ -2317,7 +2319,9 @@ static void tcp_connect_init(struct sock *sk)
          * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT.
          */
         tp->tcp_header_len = sizeof(struct tcphdr) +
-                (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0);
+                (sysctl_tcp_timestamps &&
+                (!dst_feature(dst, RTAX_FEATURE_NO_TSTAMP) ?
+                  TCPOLEN_TSTAMP_ALIGNED : 0));
 
 #ifdef CONFIG_TCP_MD5SIG
         if (tp->af_specific->md5_lookup(sk, sk) != NULL)