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(-)
