net-timestamp: only report sw timestamp if reporting bit is set

The timestamping API has separate bits for generating and reporting
timestamps. A software timestamp should only be reported for a packet
when the packet has the relevant generation flag (SKBTX_..) set
and the socket has reporting bit SOF_TIMESTAMPING_SOFTWARE set.

The second check was accidentally removed. Reinstitute the original
behavior.

Tested:
  Without this patch, Documentation/networking/txtimestamp reports
  timestamps regardless of whether SOF_TIMESTAMPING_SOFTWARE is set.
  After the patch, it only reports them when the flag is set.

Fixes: f24b9be5957b ("net-timestamp: extend SCM_TIMESTAMPING ancillary data struct")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 2 insertions, 5 deletions

diff --git a/include/net/sock.h b/include/net/sock.h
index 7f2ab72f321a..b9a5bd0ed9f3 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2165,9 +2165,7 @@ sock_recv_timestamp(struct msghdr *msg, struct sock *sk, struct sk_buff *skb)
          */
         if (sock_flag(sk, SOCK_RCVTSTAMP) ||
             (sk->sk_tsflags & SOF_TIMESTAMPING_RX_SOFTWARE) ||
-            (kt.tv64 &&
-             (sk->sk_tsflags & SOF_TIMESTAMPING_SOFTWARE ||
-              skb_shinfo(skb)->tx_flags & SKBTX_ANY_SW_TSTAMP)) ||
+            (kt.tv64 && sk->sk_tsflags & SOF_TIMESTAMPING_SOFTWARE) ||
             (hwtstamps->hwtstamp.tv64 &&
              (sk->sk_tsflags & SOF_TIMESTAMPING_RAW_HARDWARE)))
                 __sock_recv_timestamp(msg, sk, skb);
diff --git a/net/socket.c b/net/socket.c
index 95ee7d8682e7..4eb09b34b2d3 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -734,8 +734,7 @@ void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk,
         }
 
         memset(&tss, 0, sizeof(tss));
-        if ((sk->sk_tsflags & SOF_TIMESTAMPING_SOFTWARE ||
-             skb_shinfo(skb)->tx_flags & SKBTX_ANY_SW_TSTAMP) &&
+        if ((sk->sk_tsflags & SOF_TIMESTAMPING_SOFTWARE) &&
             ktime_to_timespec_cond(skb->tstamp, tss.ts + 0))
                 empty = 0;
         if (shhwtstamps &&