net: Implement missing getsockopt(SO_TIMESTAMPING_NEW)

[ Upstream commit 7f6ca95d16b96567ce4cf458a2790ff17fa620c3 ]

Commit 9718475e6908 ("socket: Add SO_TIMESTAMPING_NEW") added the new
socket option SO_TIMESTAMPING_NEW. Setting the option is handled in
sk_setsockopt(), querying it was not handled in sk_getsockopt(), though.

Following remarks on an earlier submission of this patch, keep the old
behavior of getsockopt(SO_TIMESTAMPING_OLD) which returns the active
flags even if they actually have been set through SO_TIMESTAMPING_NEW.

The new getsockopt(SO_TIMESTAMPING_NEW) is stricter, returning flags
only if they have been set through the same option.

Fixes: 9718475e6908 ("socket: Add SO_TIMESTAMPING_NEW")
Link: https://lore.kernel.org/lkml/20230703175048.151683-1-jthinz@mailbox.tu-berlin.de/
Link: https://lore.kernel.org/netdev/0d7cddc9-03fa-43db-a579-14f3e822615b@app.fastmail.com/
Signed-off-by: Jörn-Thorben Hinz <jthinz@mailbox.tu-berlin.de>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/core/sock.c b/net/core/sock.c
index bfaf47b..fe687e6 100644 (file)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1718,9 +1718,16 @@ int sk_getsockopt(struct sock *sk, int level, int optname,
                break;
 
        case SO_TIMESTAMPING_OLD:
+       case SO_TIMESTAMPING_NEW:
                lv = sizeof(v.timestamping);
-               v.timestamping.flags = READ_ONCE(sk->sk_tsflags);
-               v.timestamping.bind_phc = READ_ONCE(sk->sk_bind_phc);
+               /* For the later-added case SO_TIMESTAMPING_NEW: Be strict about only
+                * returning the flags when they were set through the same option.
+                * Don't change the beviour for the old case SO_TIMESTAMPING_OLD.
+                */
+               if (optname == SO_TIMESTAMPING_OLD || sock_flag(sk, SOCK_TSTAMP_NEW)) {
+                       v.timestamping.flags = READ_ONCE(sk->sk_tsflags);
+                       v.timestamping.bind_phc = READ_ONCE(sk->sk_bind_phc);
+               }
                break;
 
        case SO_RCVTIMEO_OLD: