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 <[email protected]> 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
