netdev - Re: [PATCH net-next v5 02/15] net-timestamp: prepare for bpf prog use

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Message-ID: <CAL+tcoA2+MO4WgzHHnX1hhCaQs6afmXWoOXNKf7wrz3QZVeeyA@mail.gmail.com>
Date: Wed, 15 Jan 2025 08:15:45 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Martin KaFai Lau <martin.lau@...ux.dev>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, 
	pabeni@...hat.com, dsahern@...nel.org, willemdebruijn.kernel@...il.com, 
	willemb@...gle.com, ast@...nel.org, daniel@...earbox.net, andrii@...nel.org, 
	eddyz87@...il.com, song@...nel.org, yonghong.song@...ux.dev, 
	john.fastabend@...il.com, kpsingh@...nel.org, sdf@...ichev.me, 
	haoluo@...gle.com, jolsa@...nel.org, horms@...nel.org, bpf@...r.kernel.org, 
	netdev@...r.kernel.org
Subject: Re: [PATCH net-next v5 02/15] net-timestamp: prepare for bpf prog use

On Wed, Jan 15, 2025 at 8:09 AM Jason Xing <kerneljasonxing@...il.com> wrote:
>
> On Wed, Jan 15, 2025 at 7:40 AM Martin KaFai Lau <martin.lau@...ux.dev> wrote:
> >
> > On 1/12/25 3:37 AM, Jason Xing wrote:
> > > Later, I would introduce three points to report some information
> > > to user space based on this.
> > >
> > > Signed-off-by: Jason Xing <kerneljasonxing@...il.com>
> > > ---
> > >   include/net/sock.h |  7 +++++++
> > >   net/core/sock.c    | 14 ++++++++++++++
> > >   2 files changed, 21 insertions(+)
> > >
> > > diff --git a/include/net/sock.h b/include/net/sock.h
> > > index f5447b4b78fd..dd874e8337c0 100644
> > > --- a/include/net/sock.h
> > > +++ b/include/net/sock.h
> > > @@ -2930,6 +2930,13 @@ int sock_set_timestamping(struct sock *sk, int optname,
> > >                         struct so_timestamping timestamping);
> > >
> > >   void sock_enable_timestamps(struct sock *sk);
> > > +#if defined(CONFIG_CGROUP_BPF) && defined(CONFIG_BPF_SYSCALL)
> > > +void bpf_skops_tx_timestamping(struct sock *sk, struct sk_buff *skb, int op);
> > > +#else
> > > +static inline void bpf_skops_tx_timestamping(struct sock *sk, struct sk_buff *skb, int op)
> > > +{
> > > +}
> > > +#endif
> > >   void sock_no_linger(struct sock *sk);
> > >   void sock_set_keepalive(struct sock *sk);
> > >   void sock_set_priority(struct sock *sk, u32 priority);
> > > diff --git a/net/core/sock.c b/net/core/sock.c
> > > index eae2ae70a2e0..e06bcafb1b2d 100644
> > > --- a/net/core/sock.c
> > > +++ b/net/core/sock.c
> > > @@ -948,6 +948,20 @@ int sock_set_timestamping(struct sock *sk, int optname,
> > >       return 0;
> > >   }
> > >
> > > +#if defined(CONFIG_CGROUP_BPF) && defined(CONFIG_BPF_SYSCALL)
> > > +void bpf_skops_tx_timestamping(struct sock *sk, struct sk_buff *skb, int op)
> > > +{
> > > +     struct bpf_sock_ops_kern sock_ops;
> > > +
> > > +     memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
> > > +     sock_ops.op = op;
> > > +     if (sk_is_tcp(sk) && sk_fullsock(sk))
> > > +             sock_ops.is_fullsock = 1;
> > > +     sock_ops.sk = sk;
> > > +     __cgroup_bpf_run_filter_sock_ops(sk, &sock_ops, CGROUP_SOCK_OPS);
> >
> > hmm... I think I have already mentioned it in the earlier revision
> > (https://lore.kernel.org/bpf/f8e9ab4a-38b9-43a5-aaf4-15f95a3463d0@linux.dev/).
>
> Right, sorry, but I deleted it intentionally.
>
> >
> > __cgroup_bpf_run_filter_sock_ops(sk, ...) requires sk to be fullsock.
>
> Well, I don't understand it, BPF_CGROUP_RUN_PROG_SOCK_OPS_SK() don't
> need to check whether it is fullsock or not.
>
> > Take a look at how BPF_CGROUP_RUN_PROG_SOCK_OPS does it.
> > sk_to_full_sk() is used to get back the listener. For other mini socks,
> > it needs to skip calling the cgroup bpf prog. I still don't understand
> > why BPF_CGROUP_RUN_PROG_SOCK_OPS cannot be used here because of udp.
>
> Sorry, I got lost here. BPF_CGROUP_RUN_PROG_SOCK_OPS cannot support
> udp, right? And I think we've discussed that we have to get rid of the
> limitation of fullsock.

To support udp case, I think I can add the following check for
__cgroup_bpf_run_filter_sock_ops() instead of directly calling
BPF_CGROUP_RUN_PROG_SOCK_OPS():
1) if the socket belongs to tcp type, it should be fullsock.
2) or if it is a udp type socket. Then no need to check and use the fullsock.

Above lines/policies should be applied to the rest of the series, right?

According to the existing callbacks, the tcp socket is indeed fullsock.

Thanks,
Jason