[PATCH 5.11 030/306] selftests/bpf: No need to drop the packet when there is no geneve opt

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

From: Hangbin Liu <redacted>

commit 557c223b643a35effec9654958d8edc62fd2603a upstream.

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 <redacted>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: William Tu <redacted>
Link: https://lore.kernel.org/bpf/20210224081403.1425474-1-liuhangbin@gmail.com (local)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 tools/testing/selftests/bpf/progs/test_tunnel_kern.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

--- 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
 	}
 
 	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);