On 10/9/26 3:49 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. Fixes: 716fa7dadf11 ("selftests/bpf: Extend netkit tests to validate skb meta data") Signed-off-by: Qiliang Yuan <[email protected]> --- tools/testing/selftests/bpf/progs/test_tc_link.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/test_tc_link.c b/tools/testing/selftests/bpf/progs/test_tc_link.c index 630f12e51b075..3c44ee06cfae8 100644 --- a/tools/testing/selftests/bpf/progs/test_tc_link.c +++ b/tools/testing/selftests/bpf/progs/test_tc_link.c @@ -4,6 +4,8 @@#include <linux/bpf.h>#include <linux/if_ether.h> +#include <linux/in.h> +#include <linux/ip.h> #include <linux/stddef.h> #include <linux/if_packet.h> #include <bpf/bpf_endian.h> @@ -119,6 +121,14 @@ SEC("tc/egress") int tc8(struct __sk_buff *skb) { struct net_device *dev = BPF_CORE_READ((struct sk_buff *)skb, dev); + __u8 proto; + + /* Look only at the ICMP echo of the test, not at IPv6 ND or mDNS */ + if (skb->protocol != bpf_htons(ETH_P_IP) || + bpf_skb_load_bytes(skb, sizeof(struct ethhdr) + offsetof(struct iphdr, protocol), + &proto, sizeof(proto)) || + proto != IPPROTO_ICMP) + return TCX_PASS;seen_tc8 = true;mark = skb->mark;
Could you streamline this a bit to be more in existing style? __bpf_constant_htons, and make the checks/error paths similar. Thanks, Daniel
