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

[Kuniyuki Iwashima]

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.


> +
>         switch (sock->type) {
>         case SOCK_STREAM:
> -               set_bit(SOCK_CUSTOM_SOCKOPT, &sock->flags);
>                 sock->ops = &unix_stream_ops;
>                 break;
>                 /*
> @@ -1864,8 +1867,7 @@ static int unix_accept(struct socket *sock, struct socket *newsock,
>         skb_free_datagram(sk, skb);
>         wake_up_interruptible(&unix_sk(sk)->peer_wait);
>
> -       if (tsk->sk_type == SOCK_STREAM)
> -               set_bit(SOCK_CUSTOM_SOCKOPT, &newsock->flags);
> +       set_bit(SOCK_CUSTOM_SOCKOPT, &newsock->flags);
>
>         /* attach accepted sock to socket */
>         unix_state_lock(tsk);
> --
> 2.55.0
>