From 200a89e3e88786b52bc1dd5f26a310c097f4c6a7 Mon Sep 17 00:00:00 2001 From: Lorenzo Bianconi Date: Wed, 25 May 2022 11:44:27 +0200 Subject: [PATCH] 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 Signed-off-by: Andrii Nakryiko 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(+) 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; + } } }