netdev - Re: [PATCH v2 net] vxlan: Fix regression when dropping packets due to invalid src addresses

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Date: Mon, 3 Jun 2024 14:49:15 +0200
From: David Bauer <mail@...id-bauer.net>
To: Daniel Borkmann <daniel@...earbox.net>, netdev@...r.kernel.org
Cc: bpf@...r.kernel.org, Ido Schimmel <idosch@...dia.com>,
 Nikolay Aleksandrov <razor@...ckwall.org>,
 Martin KaFai Lau <martin.lau@...nel.org>
Subject: Re: [PATCH v2 net] vxlan: Fix regression when dropping packets due to
 invalid src addresses



On 6/3/24 10:59, Daniel Borkmann wrote:
> Commit f58f45c1e5b9 ("vxlan: drop packets from invalid src-address")
> has recently been added to vxlan mainly in the context of source
> address snooping/learning so that when it is enabled, an entry in the
> FDB is not being created for an invalid address for the corresponding
> tunnel endpoint.
> 
> Before commit f58f45c1e5b9 vxlan was similarly behaving as geneve in
> that it passed through whichever macs were set in the L2 header. It
> turns out that this change in behavior breaks setups, for example,
> Cilium with netkit in L3 mode for Pods as well as tunnel mode has been
> passing before the change in f58f45c1e5b9 for both vxlan and geneve.
> After mentioned change it is only passing for geneve as in case of
> vxlan packets are dropped due to vxlan_set_mac() returning false as
> source and destination macs are zero which for E/W traffic via tunnel
> is totally fine.
> 
> Fix it by only opting into the is_valid_ether_addr() check in
> vxlan_set_mac() when in fact source address snooping/learning is
> actually enabled in vxlan. This is done by moving the check into
> vxlan_snoop(). With this change, the Cilium connectivity test suite
> passes again for both tunnel flavors.
> 
> Fixes: f58f45c1e5b9 ("vxlan: drop packets from invalid src-address")
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
> Cc: David Bauer <mail@...id-bauer.net>
> Cc: Ido Schimmel <idosch@...dia.com>
> Cc: Nikolay Aleksandrov <razor@...ckwall.org>
> Cc: Martin KaFai Lau <martin.lau@...nel.org>

Reviewed-by: David Bauer <mail@...id-bauer.net>

Best
David