Re: [PATCH bpf-next v2] selftests/bpf: Record only the test ICMP echo in tc8 of tc_netkit_scrub

[Daniel Borkmann <daniel@iogearbox.net>]

On 10/16/26 5:25 AM, Qiliang Yuan wrote:
> tc_netkit_scrub attaches tc8 to the primary netkit device, sends an ICMP
> echo with a mark and a priority through it, and checks the mark and the
> priority that tc8 saw against what the scrub mode lets through.
> 
> tc8 records the mark and priority of every packet it sees, and the
> device also carries what the system sends on its own once the device
> is up, like IPv6 neighbor discovery or the mDNS of avahi-daemon. When
> such a packet goes out after the echo, it overwrites what tc8 recorded,
> and the test finds a mark and a priority of 0.
> 
> Record only IPv4 ICMP packets in tc8.
> 
> tc_netkit_scrub run 100 times on a bpf-next kernel with KASAN enabled,
> x86_64 VM with 32 vCPUs and avahi-daemon running, before and after this
> patch:
> 
>              before                                after
>    outcome   2 of 100 failed (mark and priority 0)   0 of 100 failed
> 
> Fixes: 716fa7dadf11 ("selftests/bpf: Extend netkit tests to validate skb meta data")
> Signed-off-by: Qiliang Yuan <odys.yuan@gmail.com>
> ---
> V1 -> V2:
> - Check the packet in tc8 the way tc1 and tc7 do, with
>    __bpf_constant_htons() and a goto out for each check (Daniel)
> - Add before/after data
Looks good, took this into bpf-next, thanks!