Re: [PATCH net-next v5 1/5] net: udp: add freebind option to udp_sock_create

[Richard Gobert]

Ido Schimmel wrote:
> On Tue, Aug 12, 2025 at 02:51:51PM +0200, Richard Gobert wrote:
>> udp_sock_create creates a UDP socket and binds it according to
>> udp_port_cfg.
>>
>> Add a freebind option to udp_port_cfg that allows a socket to be bound
>> as though IP_FREEBIND is set.
>>
>> This change is required for binding vxlan sockets to their local address
>> when the outgoing interface is down.
> 
> It's not necessarily the outgoing interface, but rather the interface to
> which the address is assigned.
> 
> Anyway, I'm not sure this change is actually necessary. It was only
> added in v4 because back then the default behavior was changed to bind
> the VXLAN socket to the local address and existing selftests do not
> necessarily configure the address before putting the VXLAN device up.
> 
> Given that in this version binding the VXLAN socket to the local address
> is opt-in, it seems legitimate to prevent user space from putting the
> VXLAN device up if the new option is enabled and the local address is
> not present. It can also be documented in the man page so that users are
> not surprised.

Sounds good, will change in v6.