From 200a89e3e88786b52bc1dd5f26a310c097f4c6a7 Mon Sep 17 00:00:00 2001
From: Lorenzo Bianconi <lorenzo@kernel.org>
Date: Wed, 25 May 2022 11:44:27 +0200
Subject: sample: bpf: xdp_router_ipv4: Allow the kernel to send arp requests
Forward the packet to the kernel if the gw router mac address is missing
in to trigger ARP discovery.
Fixes: 85bf1f51691c ("samples: bpf: Convert xdp_router_ipv4 to XDP samples helper")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/60bde5496d108089080504f58199bcf1143ea938.1653471558.git.lorenzo@kernel.org
---
samples/bpf/xdp_router_ipv4.bpf.c | 9 +++++++++
1 file changed, 9 insertions(+)
(limited to 'samples')
diff --git a/samples/bpf/xdp_router_ipv4.bpf.c b/samples/bpf/xdp_router_ipv4.bpf.c
index 248119ca7938..0643330d1d2e 100644
--- a/samples/bpf/xdp_router_ipv4.bpf.c
+++ b/samples/bpf/xdp_router_ipv4.bpf.c
@@ -150,6 +150,15 @@ int xdp_router_ipv4_prog(struct xdp_md *ctx)
dest_mac = bpf_map_lookup_elem(&arp_table,
&prefix_value->gw);
+ if (!dest_mac) {
+ /* Forward the packet to the kernel in
+ * order to trigger ARP discovery for
+ * the default gw.
+ */
+ if (rec)
+ NO_TEAR_INC(rec->xdp_pass);
+ return XDP_PASS;
+ }
}
}
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