netdev - [PATCH net] selftest/bpf: no need to drop the packet when there is no geneve opt

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Date:   Wed, 24 Feb 2021 16:14:03 +0800
From:   Hangbin Liu <liuhangbin@...il.com>
To:     netdev@...r.kernel.org
Cc:     Jakub Kicinski <kuba@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Yi-Hung Wei <yihung.wei@...il.com>,
        David Miller <davem@...emloft.net>, bpf@...r.kernel.org,
        Jiong Wang <jiong.wang@...ronome.com>,
        Hangbin Liu <liuhangbin@...il.com>
Subject: [PATCH net] selftest/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.

Signed-off-by: Hangbin Liu <liuhangbin@...il.com>
---
 tools/testing/selftests/bpf/progs/test_tunnel_kern.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/test_tunnel_kern.c b/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
index a621b58ab079..9afe947cfae9 100644
--- 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);
-- 
2.26.2