net-timestamp: extend SCM_TIMESTAMPING ancillary data struct

Applications that request kernel tx timestamps with SO_TIMESTAMPING
read timestamps as recvmsg() ancillary data. The response is defined
implicitly as timespec[3].

1) define struct scm_timestamping explicitly and

2) add support for new tstamp types. On tx, scm_timestamping always
   accompanies a sock_extended_err. Define previously unused field
   ee_info to signal the type of ts[0]. Introduce SCM_TSTAMP_SND to
   define the existing behavior.

The reception path is not modified. On rx, no struct similar to
sock_extended_err is passed along with SCM_TIMESTAMPING.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/include/net/sock.h b/include/net/sock.h
index b91c8868ab8d..02f5b35e65f1 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2169,7 +2169,9 @@ sock_recv_timestamp(struct msghdr *msg, struct sock *sk, struct sk_buff *skb)
          */
         if (sock_flag(sk, SOCK_RCVTSTAMP) ||
             sock_flag(sk, SOCK_TIMESTAMPING_RX_SOFTWARE) ||
-            (kt.tv64 && sock_flag(sk, SOCK_TIMESTAMPING_SOFTWARE)) ||
+            (kt.tv64 &&
+             (sock_flag(sk, SOCK_TIMESTAMPING_SOFTWARE) ||
+              skb_shinfo(skb)->tx_flags & SKBTX_ANY_SW_TSTAMP)) ||
             (hwtstamps->hwtstamp.tv64 &&
              sock_flag(sk, SOCK_TIMESTAMPING_RAW_HARDWARE)))
                 __sock_recv_timestamp(msg, sk, skb);