netdev - Re: [PATCH net-next 7/9] net-timestamp: open gate for bpf

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAL+tcoBGe83v+1ej6GYpZpDkFt_hnuzw_mG8E3vEEhSQbUkreA@mail.gmail.com>
Date: Wed, 9 Oct 2024 16:09:19 +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, bpf@...r.kernel.org, 
	netdev@...r.kernel.org, Jason Xing <kernelxing@...cent.com>
Subject: Re: [PATCH net-next 7/9] net-timestamp: open gate for bpf_setsockopt

On Wed, Oct 9, 2024 at 3:19 PM Martin KaFai Lau <martin.lau@...ux.dev> wrote:
>
> On 10/8/24 2:51 AM, Jason Xing wrote:
> > From: Jason Xing <kernelxing@...cent.com>
> >
> > Now we allow users to set tsflags through bpf_setsockopt. What I
> > want to do is passing SOF_TIMESTAMPING_RX_SOFTWARE flag, so that
> > we can generate rx timestamps the moment the skb traverses through
> > driver.
> >
> > Here is an example:
> >
> > case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
> > case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
> >       sock_opt = SOF_TIMESTAMPING_RX_SOFTWARE;
> >       bpf_setsockopt(skops, SOL_SOCKET, SO_TIMESTAMPING,
> >                      &sock_opt, sizeof(sock_opt));
> >       break;
> >
> > In this way, we can use bpf program that help us generate and report
> > rx timestamp.
> >
> > Signed-off-by: Jason Xing <kernelxing@...cent.com>
> > ---
> >   net/core/filter.c | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/net/core/filter.c b/net/core/filter.c
> > index bd0d08bf76bb..9ce99d320571 100644
> > --- a/net/core/filter.c
> > +++ b/net/core/filter.c
> > @@ -5225,6 +5225,9 @@ static int sol_socket_sockopt(struct sock *sk, int optname,
> >               break;
> >       case SO_BINDTODEVICE:
> >               break;
> > +     case SO_TIMESTAMPING_NEW:
> > +     case SO_TIMESTAMPING_OLD:
>
> I believe this change was proposed before. It will change the user expectation
> on the sk_error_queue. It needs some bits/fields/knobs for bpf. I think this
> point is similar to other's earlier comments in this thread.

Thanks for your reply.

After seeing what you mentioned, I searched through the mailing list
and found one [1] which was designed to fetch hardware timestamps.

[1]：https://lore.kernel.org/bpf/51fd5249-140a-4f1b-b20e-703f159e88a3@linux.dev/T/

>
> I only have a chance to briefly look at it. I think it is useful. This
> bpf/timestamp feature request has come up before.

At the very beginning, I had no intention to use bpf_setsockopt() to
retrieve the rx timestamp because it will override sk_tsflags, but I
cannot implement a good way like what I did to tx path: only setting
skb's field. I'm not sure if this override behaviour is acceptable, so
I post it to know what the bpf experts' suggestions are.

>
> A high level comment. The current timestamp should work for non tcp sock? The
> bpf/timestamp solution should be able to also.

For now, it only supports TCP proto. I would like to quickly implement
a framework which is also suitable for other protos. TCP is just a
start point.

>
> sockops is tcp centric. From looking at patch 9 that needs to initialize 4 args,
> this interface feels old and not sure we want to extend to other sock types.
> This needs some thoughts.

For me, I have interests to extend to other sock types. But I'm
supposed to ask Willem's opinion first.

+Willem de Bruijn Do you want this bpf extension feature to extend to
other protos?

Thanks,
Jason