Hello everybody,
I am testing eBPF programs on ipv6 and I just find out the tcp_filter() function (previously named sk_filter()) is called both in tcp_v6_rcv() and tcp_v6_do_rcv(). In contrast, it is only called by tcp_v4_rcv() in ipv4 layer. I guess this implementation is used to capture some corner cases in ipv6 ingress route but I cannot find why. Could I know why we need this in two similar places in ipv6 transportation layer?
I have tried to dig into the commit history and the related code path but I did not see any obvious reason for doing so. And my problem with it is when a eBPF program is attached to a socket or a cgroup in ingress side, the filter program will be applied on some packets twice. And it affect the accuracy when using eBPF program for traffic accounting.
Thanks!
Chenbo Feng
On Wed, 2017-06-07 at 15:35 -0700, Chenbo Feng wrote:
Hello everybody,
I am testing eBPF programs on ipv6 and I just find out the tcp_filter()
function (previously named sk_filter()) is called both in tcp_v6_rcv()
and tcp_v6_do_rcv(). In contrast, it is only called by tcp_v4_rcv() in
ipv4 layer. I guess this implementation is used to capture some corner
cases in ipv6 ingress route but I cannot find why. Could I know why we
need this in two similar places in ipv6 transportation layer?
I have tried to dig into the commit history and the related code path
but I did not see any obvious reason for doing so. And my problem with
it is when a eBPF program is attached to a socket or a cgroup in ingress
side, the filter program will be applied on some packets twice. And it
affect the accuracy when using eBPF program for traffic accounting.
It seems this was added in this commit
commit 5234b9f7d650fe64975695d835cb9413e1d75f46
Author: James Morris [off-list ref]
Date: Thu Feb 6 09:49:40 2003 -0800
[LSM]: Networking socket SKB receive hook.
You can find the history tree in :
[remote "origin"]
url = git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
fetch = +refs/heads/*:refs/remotes/origin/*
The call from tcp_v6_do_rcv() should be removed I guess