From: Martin KaFai Lau <martin.lau@xxxxxxxxx>
Date: Mon, 16 Oct 2023 11:33:36 -0700
> On 10/12/23 11:11 AM, Kuniyuki Iwashima wrote:
> > From: Daan De Meyer <daan.j.demeyer@xxxxxxxxx>
> > Date: Thu, 12 Oct 2023 10:52:13 +0200
> >> Changes since v1:
> >>
> >> * Added missing Signed-off-by tag
> >
> > You can put these after --- so that it will disappear when merged.
> >
> >
> >>
> >> We should not run the recvmsg() hooks on unnamed sockets as we do
> >> not run them on unnamed sockets in the other hooks either. We may
> >> look into relaxing this later but for now let's make sure we are
> >> consistent and not run the hooks on unnamed sockets anywhere.
> >>
> >> Signed-off-by: Daan De Meyer <daan.j.demeyer@xxxxxxxxx>
> >> ---
> >> net/unix/af_unix.c | 14 ++++++++------
> >> 1 file changed, 8 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> >> index e10d07c76044..81fb8bddaff9 100644
> >> --- a/net/unix/af_unix.c
> >> +++ b/net/unix/af_unix.c
> >> @@ -2416,9 +2416,10 @@ int __unix_dgram_recvmsg(struct sock *sk, struct msghdr *msg, size_t size,
> >> if (msg->msg_name) {
> >> unix_copy_addr(msg, skb->sk);
> >
> > How is an unnamed socket set to skb->sk ?
>
> I had a similar question. Most likely socketpair? Please add an explanation in
> the commit message in v3. Please also help to add a selftest for this case.
Ah exactly, socketpair() for SOCK_STREAM does it.
>
> >
> >
> >>
> >> - BPF_CGROUP_RUN_PROG_UNIX_RECVMSG_LOCK(sk,
> >> - msg->msg_name,
> >> - &msg->msg_namelen);
> >> + if (msg->msg_namelen > 0)
> >> + BPF_CGROUP_RUN_PROG_UNIX_RECVMSG_LOCK(sk,
> >> + msg->msg_name,
> >> + &msg->msg_namelen);
> >> }
> >>
> >> if (size > skb->len - skip)
> >> @@ -2773,9 +2774,10 @@ static int unix_stream_read_generic(struct unix_stream_read_state *state,
> >> state->msg->msg_name);
> >> unix_copy_addr(state->msg, skb->sk);
> >>
> >> - BPF_CGROUP_RUN_PROG_UNIX_RECVMSG_LOCK(sk,
> >> - state->msg->msg_name,
> >> - &state->msg->msg_namelen);
> >> + if (state->msg->msg_namelen > 0)
> >> + BPF_CGROUP_RUN_PROG_UNIX_RECVMSG_LOCK(sk,
> >> + state->msg->msg_name,
> >> + &state->msg->msg_namelen);
> >>
> >> sunaddr = NULL;
> >> }
> >> --
> >> 2.41.0
