Re: [PATCH v15 4/9] arp/ndp: send ARP announcement / unsolicited NA when neigbour entry added

[David Gibson <david@gibson.dropbear.id.au>]

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On Thu, Oct 23, 2025 at 09:29:28PM -0400, Jon Maloy wrote:
> ARP announcements and unsolicited NAs should be handled with caution
> because of the risk of malignant users emitting them to disturb
> network communication.
> 
> There is however one case we where we know it is legitimate
> and safe for us to send out such messages: The one time we switch
> from using ctx->own_tap_mac to a MAC address received via the
> recently added neigbour subscription function. Later changes to
> the MAC address of a host in an existing entry cannot be fully
> trusted, so we abstain from doing it in such cases.
> 
> When sending this type of messages, we notice that the guest accepts
> the update, but shortly later asks for a confirmation in the form of
> a regular ARP/NS request. This is responded to with the new value,
> and we have exactly the effect we wanted.
> 
> This commit adds this functionality.
> 
> Signed-off-by: Jon Maloy <jmaloy@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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