| Message ID | 20201009103121.1004-2-ceggers@arri.de (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,1/2] socket: fix option SO_TIMESTAMPING_NEW | expand |
On Fri, Oct 9, 2020 at 6:32 AM Christian Eggers <ceggers@arri.de> wrote: > > SOCK_TSTAMP_NEW (timespec64 instead of timespec) is also used for > hardware time stamps (configured via SO_TIMESTAMPING_NEW). > > User space (ptp4l) first configures hardware time stamping via > SO_TIMESTAMPING_NEW which sets SOCK_TSTAMP_NEW. In the next step, ptp4l > disables SO_TIMESTAMPNS(_NEW) (software time stamps), but this must not > switch hardware time stamps back to "32 bit mode". > > This problem happens on 32 bit platforms were the libc has already > switched to struct timespec64 (from SO_TIMExxx_OLD to SO_TIMExxx_NEW > socket options). ptp4l complains with "missing timestamp on transmitted > peer delay request" because the wrong format is received (and > discarded). > > Fixes: 887feae36aee ("socket: Add SO_TIMESTAMP[NS]_NEW") > Fixes: 783da70e8396 ("net: add sock_enable_timestamps") > Signed-off-by: Christian Eggers <ceggers@arri.de> Acked-by: Willem de Bruijn <willemb@google.com> Yes, we should just select SOCK_TSTAMP_NEW based on which of the two syscall variants the process uses. There is no need to reset on timestamp disable: in the common case the selection is immaterial as timestamping is disabled. As this commit message shows, with SO_TIMESTAMP(NS) and SO_TIMESTAMPING that can be independently turned on and off, disabling one can incorrectly switch modes while the other is still active.
On Fri, Oct 9, 2020 at 5:35 PM Willem de Bruijn <willemdebruijn.kernel@gmail.com> wrote: > > On Fri, Oct 9, 2020 at 6:32 AM Christian Eggers <ceggers@arri.de> wrote: > > > > SOCK_TSTAMP_NEW (timespec64 instead of timespec) is also used for > > hardware time stamps (configured via SO_TIMESTAMPING_NEW). > > > > User space (ptp4l) first configures hardware time stamping via > > SO_TIMESTAMPING_NEW which sets SOCK_TSTAMP_NEW. In the next step, ptp4l > > disables SO_TIMESTAMPNS(_NEW) (software time stamps), but this must not > > switch hardware time stamps back to "32 bit mode". > > > > This problem happens on 32 bit platforms were the libc has already > > switched to struct timespec64 (from SO_TIMExxx_OLD to SO_TIMExxx_NEW > > socket options). ptp4l complains with "missing timestamp on transmitted > > peer delay request" because the wrong format is received (and > > discarded). > > > > Fixes: 887feae36aee ("socket: Add SO_TIMESTAMP[NS]_NEW") > > Fixes: 783da70e8396 ("net: add sock_enable_timestamps") > > Signed-off-by: Christian Eggers <ceggers@arri.de> > > Acked-by: Willem de Bruijn <willemb@google.com> > > Yes, we should just select SOCK_TSTAMP_NEW based on which of the two > syscall variants the process uses. > > There is no need to reset on timestamp disable: in the common case the > selection is immaterial as timestamping is disabled. > > As this commit message shows, with SO_TIMESTAMP(NS) and > SO_TIMESTAMPING that can be independently turned on and off, disabling > one can incorrectly switch modes while the other is still active. This will not help the case when a child process that inherits the fd and then sets SO_TIMESTAMP*_OLD/NEW on it, while the parent uses the other version. One of the two processes might still be surprised. But, child and parent actively using the same socket fd might be expecting trouble already. Acked-by: Deepa Dinamani <deepa.kernel@gmail.com> -Deepa
diff --git a/net/core/sock.c b/net/core/sock.c index 3926804702c1..f09053dfb12c 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -757,7 +757,6 @@ static void __sock_set_timestamps(struct sock *sk, bool val, bool new, bool ns) } else { sock_reset_flag(sk, SOCK_RCVTSTAMP); sock_reset_flag(sk, SOCK_RCVTSTAMPNS); - sock_reset_flag(sk, SOCK_TSTAMP_NEW); } }
SOCK_TSTAMP_NEW (timespec64 instead of timespec) is also used for hardware time stamps (configured via SO_TIMESTAMPING_NEW). User space (ptp4l) first configures hardware time stamping via SO_TIMESTAMPING_NEW which sets SOCK_TSTAMP_NEW. In the next step, ptp4l disables SO_TIMESTAMPNS(_NEW) (software time stamps), but this must not switch hardware time stamps back to "32 bit mode". This problem happens on 32 bit platforms were the libc has already switched to struct timespec64 (from SO_TIMExxx_OLD to SO_TIMExxx_NEW socket options). ptp4l complains with "missing timestamp on transmitted peer delay request" because the wrong format is received (and discarded). Fixes: 887feae36aee ("socket: Add SO_TIMESTAMP[NS]_NEW") Fixes: 783da70e8396 ("net: add sock_enable_timestamps") Signed-off-by: Christian Eggers <ceggers@arri.de> --- net/core/sock.c | 1 - 1 file changed, 1 deletion(-)