[0/2] ipv4, bpf: Introduced to support the ULP to get or set sockets

Message

zhangmingyi Jan. 27, 2025, 9:07 a.m. UTC

We want 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 fastopen to implement delayed
connet and perform HTTP DNAT when sendmsg.In this case, we need to parse
HTTP packets in the bpf program and set TCP_ULP for the specified socket.

Note that tcp_getsockopt and tcp_setsockopt support TCP_ULP, while
bpf_getsockopt and bpf_setsockopt do not support TCP_ULP.
I'm not sure why there is such a difference, but I noticed that
tcp_setsockopt is called in bpf_setsockopt.I think we can add the
handling of this case.

zhangmingyi (2):
  ipv4, bpf: Introduced to support the ULP to get or set sockets
  add selftest for TCP_ULP in bpf_setsockopt

 net/core/filter.c                             |  1 +
 .../selftests/bpf/progs/setget_sockopt.c      | 21 ++++++++++++++++---
 2 files changed, 19 insertions(+), 3 deletions(-)

Comments

Martin KaFai Lau Jan. 29, 2025, 8:58 p.m. UTC | #1

On 1/27/25 1:07 AM, zhangmingyi wrote:
> We want 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 fastopen to implement delayed
> connet and perform HTTP DNAT when sendmsg.In this case, we need to parse
> HTTP packets in the bpf program and set TCP_ULP for the specified socket.

The ulp could be a kernel module. Which ulp is needed in your use case?

> Note that tcp_getsockopt and tcp_setsockopt support TCP_ULP, while
> bpf_getsockopt and bpf_setsockopt do not support TCP_ULP.
> I'm not sure why there is such a difference, but I noticed that

You are right that bpf_get/setsockopt should be able to support most of the 
TCP_* optname.

After looking at tcp_set_ulp, I believe TCP_ULP is one of the few exceptions. I 
didn't drill down further and I stopped at __tcp_ulp_find_autoload which I 
believe it might_sleep. The BPF programs that support bpf_setsockopt cannot 
sleep. Take a look at how do_tcp_setsockopt(TCP_CONGESTION) is done.

pw-bot: cr

> tcp_setsockopt is called in bpf_setsockopt.I think we can add the
> handling of this case.
> 
> zhangmingyi (2):
>    ipv4, bpf: Introduced to support the ULP to get or set sockets
>    add selftest for TCP_ULP in bpf_setsockopt
> 
>   net/core/filter.c                             |  1 +
>   .../selftests/bpf/progs/setget_sockopt.c      | 21 ++++++++++++++++---
>   2 files changed, 19 insertions(+), 3 deletions(-)
>