selftests/bpf: No need to drop the packet when there is no geneve opt

In bpf geneve tunnel test we set geneve option on tx side. On rx side we
only call bpf_skb_get_tunnel_opt(). Since commit 9c2e14b48119 ("ip_tunnels:
Set tunnel option flag when tunnel metadata is present") geneve_rx() will
not add TUNNEL_GENEVE_OPT flag if there is no geneve option, which cause
bpf_skb_get_tunnel_opt() return ENOENT and _geneve_get_tunnel() in
test_tunnel_kern.c drop the packet.

As it should be valid that bpf_skb_get_tunnel_opt() return error when
there is not tunnel option, there is no need to drop the packet and
break all geneve rx traffic. Just set opt_class to 0 in this test and
keep returning TC_ACT_OK.

Fixes: 933a741e3b82 ("selftests/bpf: bpf tunnel test.")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: William Tu <u9012063@gmail.com>
Link: https://lore.kernel.org/bpf/20210224081403.1425474-1-liuhangbin@gmail.com

diff --git a/tools/testing/selftests/bpf/progs/test_tunnel_kern.c b/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
index a621b58..9afe947 100644 (file)
--- a/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
+++ b/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
@@ -446,10 +446,8 @@ int _geneve_get_tunnel(struct __sk_buff *skb)
        }
 
        ret = bpf_skb_get_tunnel_opt(skb, &gopt, sizeof(gopt));
-       if (ret < 0) {
-               ERROR(ret);
-               return TC_ACT_SHOT;
-       }
+       if (ret < 0)
+               gopt.opt_class = 0;
 
        bpf_trace_printk(fmt, sizeof(fmt),
                        key.tunnel_id, key.remote_ipv4, gopt.opt_class);