On Wed, Apr 17, 2019 at 12:19 PM Arnd Bergmann <arnd@xxxxxxxx> wrote: > > On Wed, Apr 17, 2019 at 4:46 PM Willem de Bruijn > <willemdebruijn.kernel@xxxxxxxxx> wrote: > > On Tue, Apr 16, 2019 at 4:38 PM Arnd Bergmann <arnd@xxxxxxxx> wrote: > > > The SIOCGSTAMP/SIOCGSTAMPNS ioctl commands are implemented by many > > > socket protocol handlers, and all of those end up calling the same > > > sock_get_timestamp()/sock_get_timestampns() helper functions, which > > > results in a lot of duplicate code. > > > > > > With the introduction of 64-bit time_t on 32-bit architectures, this > > > gets worse, as we then need four different ioctl commands in each > > > socket protocol implementation. > > > > > > To simplify that, let's add a new .gettstamp() operation in > > > struct proto_ops, and move ioctl implementation into the common > > > sock_ioctl()/compat_sock_ioctl_trans() functions that these all go > > > through. > > > > > > We can reuse the sock_get_timestamp() implementation, but generalize > > > it so it can deal with both native and compat mode, as well as > > > timeval and timespec structures. > > > > > > Acked-by: Stefan Schmidt <stefan@xxxxxxxxxxxxxxxxxx> > > > Link: https://lore.kernel.org/lkml/CAK8P3a038aDQQotzua_QtKGhq8O9n+rdiz2=WDCp82ys8eUT+A@xxxxxxxxxxxxxx/ > > > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> > > > --- > > > v2: reworked to not break sparc64 support > > > > From the discussion of v1 I thought you planned to unconditionally > > call sock_gettstamp() for all protocols, avoiding the need to plumb in > > all these new callbacks? > > > > That is more concise, though this closer to the existing behavior. So, > > fine either way. > > Thanks for the reminder. I have definitely waited too long before revisiting > this series, and only had a vague recollection of that discussion but could > not find it in the logs (found it now, and the Link I quoted...). > > I would prefer to get this series into the coming merge window, and > probably don't have time to rework it completely by then, so I hope > the current version is ok. Absolutely. This is a great simplification either way. > I also found your comment on lock_sock(), which could be easily > added inside of sock_gettstamp() if you think we should have that. To remind, the issue is that sock_enable_timestamp should update both sk_flags and net_enable_timestamp as one atomic operation, by holding the socket lock. The lock is held when called from a setsockopt path. And from some ioctl() implementations. The syzkaller reproducer triggered through inet_release, so the most widely used paths are buggy today. Since the current state is inconsistent already, we can defer the fix. I expect that it is now safe to add a lock around this logic without triggering lockdep issues in any of the numerous paths. But just in case, it still seems safer to do that in a separate patch that we can revert or rework independent from this, if that would prove necessary. > There is one more issue I just noticed (I dropped the necessary > sock_read_timestamp()), so I have to repost the series anyway > to fix that. Instead of reading sk->sk_stamp directly? Yes, makes sense.
