Re: [PATCH] ipv4, bpf: Introduced to support the ULP to modify sockets during setopt

[zhangmingyi <zhangmingyi5@huawei.com>]

We want to call `bpf_setsockopt` to replace the kernel module in the TCP_ULP case. The purpose is to customize the behavior in `connect` and `sendmsg`. We have an open-source community project kmesh (kmesh.net). Based on this, we refer to some processes of TCP Fast Open to implement delayed connect and perform HTTP DNAT when `sendmsg`.

I'll send a patch with a full description and test cases later.

> > Signed-off-by: zhangmingyi <zhangmingyi5@huawei.com>
> > ---
> >   net/core/filter.c | 4 ++++
> >   1 file changed, 4 insertions(+)
> > 
> > diff --git a/net/core/filter.c b/net/core/filter.c
> > index 713d6f454df3..f23d3f87e690 100644
> > --- a/net/core/filter.c
> > +++ b/net/core/filter.c
> > @@ -5383,6 +5383,10 @@ static int sol_tcp_sockopt(struct sock *sk, int optname,
> >             if (*optlen < 1)
> >                     return -EINVAL;
> >             break;
> > +   case TCP_ULP:
> > +           if (getopt)
> > +                   return -EINVAL;
> > +           break;
> >     case TCP_BPF_SOCK_OPS_CB_FLAGS:
> >             if (*optlen != sizeof(int))
> >                     return -EINVAL;
>