Re: [net-next v5 1/4] net: af_unix: enable custom setsockopt for all socket types

[Kuniyuki Iwashima]

On Tue, Jul 28, 2026 at 4:05 PM Jori Koolstra <jkoolstra@xxxxxxxxx> wrote:
>
> @Kuniyuki,
>
> Could you take a look at this if you have time? Would like to move this
> along if we can.

Sorry for the delay, I was on vacation for two weeks.

>
> Thanks,
> Jori.
>
> > Op 19-07-2026 14:31 CEST schreef Jori Koolstra <jkoolstra@xxxxxxxxx>:
> >
> >
> > > Op 14-07-2026 11:19 CEST schreef Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>:
> > >
> > >
> > > On Sun, Jul 12, 2026 at 9:29 PM Jori Koolstra <jkoolstra@xxxxxxxxx> wrote:
> > > >
> > > > unix_setsockopt() and the SOCK_CUSTOM_SOCKOPT flag were only wired up
> > > > for SOCK_STREAM (introduced along with the stream-only SO_INQ).
> > > > Consequently custom AF_UNIX options are unreachable on SOCK_DGRAM and
> > > > SOCK_SEQPACKET: those setsockopt() calls bypass unix_setsockopt() and
> > > > fall through to the generic sock_setsockopt(), failing with
> > > > -ENOPROTOOPT.
> > > >
> > > > Set SOCK_CUSTOM_SOCKOPT for every AF_UNIX socket type in unix_create(), and
> > > > also for accepted sockets in unix_accept() (reachable for stream and
> > > > seqpacket).
> > > >
> > > > This is a prerequisite for making SO_RIGHTS_NOTRUNC settable on all AF_UNIX
> > > > socket types.
> > > >
> > > > Signed-off-by: Jori Koolstra <jkoolstra@xxxxxxxxx>
> > > > ---
> > > >  net/unix/af_unix.c | 10 ++++++----
> > > >  1 file changed, 6 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> > > > index f7a9d55eee8a..3d256255085b 100644
> > > > --- a/net/unix/af_unix.c
> > > > +++ b/net/unix/af_unix.c
> > > > @@ -949,7 +949,7 @@ static int unix_setsockopt(struct socket *sock, int level, int optname,
> > > >         switch (optname) {
> > > >         case SO_INQ:
> > > >                 if (sk->sk_type != SOCK_STREAM)
> > > > -                       return -EINVAL;
> > > > +                       return -ENOPROTOOPT;
> > > >
> > > >                 if (val > 1 || val < 0)
> > > >                         return -EINVAL;
> > > > @@ -1005,6 +1005,7 @@ static const struct proto_ops unix_dgram_ops = {
> > > >  #endif
> > > >         .listen =       sock_no_listen,
> > > >         .shutdown =     unix_shutdown,
> > > > +       .setsockopt =   unix_setsockopt,
> > > >         .sendmsg =      unix_dgram_sendmsg,
> > > >         .read_skb =     unix_read_skb,
> > > >         .recvmsg =      unix_dgram_recvmsg,
> > > > @@ -1029,6 +1030,7 @@ static const struct proto_ops unix_seqpacket_ops = {
> > > >  #endif
> > > >         .listen =       unix_listen,
> > > >         .shutdown =     unix_shutdown,
> > > > +       .setsockopt =   unix_setsockopt,
> > > >         .sendmsg =      unix_seqpacket_sendmsg,
> > > >         .recvmsg =      unix_seqpacket_recvmsg,
> > > >         .mmap =         sock_no_mmap,
> > > > @@ -1142,9 +1144,10 @@ static int unix_create(struct net *net, struct socket *sock, int protocol,
> > > >         if (protocol && protocol != PF_UNIX)
> > > >                 return -EPROTONOSUPPORT;
> > > >
> > > > +       set_bit(SOCK_CUSTOM_SOCKOPT, &sock->flags);
> > >
> > > Please move this to unix_create1(), then we don't need the chunk below.
> > >
> > >
> >
> > I don't understand how this helps. The accept() path gets its struct socket from
> > sock_alloc() not via unix_create() afaict. Also, unix_create1() is called with
> > sock == NULL on connect(), so now you have to guard against that too.

It seems I misread sk/sock.  Please keep set_bit() as is.

Thanks !

> >
> > But maybe I misunderstand you?
> >
> > I do agree with you other comment, accept() should probably inherit the truncate
> > behavior from the listen() socket.
> >
> > Thanks,
> > Jori.