tcp: set and get per-socket timestamp

A timestamp can be set, only if a socket is in the repair mode.

This patch adds a new socket option TCP_TIMESTAMP, which allows to
get and set current tcp times stamp.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: James Morris <jmorris@namei.org>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 10 insertions, 0 deletions

diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index e962faa5ab0d..6b1ead0b0c9d 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -111,6 +111,7 @@ enum {
 #define TCP_QUEUE_SEQ           21
 #define TCP_REPAIR_OPTIONS      22
 #define TCP_FASTOPEN            23      /* Enable FastOpen on listeners */
+#define TCP_TIMESTAMP           24
 
 struct tcp_repair_opt {
         __u32   opt_code;
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 8a90bda96038..801b07b796f0 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2714,6 +2714,12 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
                 else
                         err = -EINVAL;
                 break;
+        case TCP_TIMESTAMP:
+                if (!tp->repair)
+                        err = -EPERM;
+                else
+                        tp->tsoffset = val - tcp_time_stamp;
+                break;
         default:
                 err = -ENOPROTOOPT;
                 break;
@@ -2962,6 +2968,9 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
         case TCP_USER_TIMEOUT:
                 val = jiffies_to_msecs(icsk->icsk_user_timeout);
                 break;
+        case TCP_TIMESTAMP:
+                val = tcp_time_stamp + tp->tsoffset;
+                break;
         default:
                 return -ENOPROTOOPT;
         }