Re: [PATCH ipsec-next,v4 1/3] net: allow storing xfrm interface metadata in metadata_dst

[Nicolas Dichtel <nicolas.dichtel@6wind.com>]

Le 26/08/2022 à 13:46, Eyal Birger a écrit :
> XFRM interfaces provide the association of various XFRM transformations
> to a netdevice using an 'if_id' identifier common to both the XFRM data
> structures (polcies, states) and the interface. The if_id is configured by
> the controlling entity (usually the IKE daemon) and can be used by the
> administrator to define logical relations between different connections.
> 
> For example, different connections can share the if_id identifier so
> that they pass through the same interface, . However, currently it is
> not possible for connections using a different if_id to use the same
> interface while retaining the logical separation between them, without
> using additional criteria such as skb marks or different traffic
> selectors.
> 
> When having a large number of connections, it is useful to have a the
> logical separation offered by the if_id identifier but use a single
> network interface. Similar to the way collect_md mode is used in IP
> tunnels.
> 
> This patch attempts to enable different configuration mechanisms - such
> as ebpf programs, LWT encapsulations, and TC - to attach metadata
> to skbs which would carry the if_id. This way a single xfrm interface in
> collect_md mode can demux traffic based on this configuration on tx and
> provide this metadata on rx.
> 
> The XFRM metadata is somewhat similar to ip tunnel metadata in that it
> has an "id", and shares similar configuration entities (bpf, tc, ...),
> however, it does not necessarily represent an IP tunnel or use other
> ip tunnel information, and also has an optional "link" property which
> can be used for affecting underlying routing decisions.
> 
> Additional xfrm related criteria may also be added in the future.
> 
> Therefore, a new metadata type is introduced, to be used in subsequent
> patches in the xfrm interface and configuration entities.
> 
> Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
> Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
Reviewed-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>