Re: [PATCH ipsec-next,v4 0/3] xfrm: support collect metadata mode for xfrm interfaces

[Steffen Klassert <steffen.klassert@secunet.com>]

On Fri, Aug 26, 2022 at 02:46:57PM +0300, Eyal Birger wrote:
> This series adds support for "collect_md" mode in XFRM interfaces.
> 
> This feature is useful for maintaining a large number of IPsec connections
> with the benefits of using a network interface while reducing the overhead
> of maintaining a large number of devices.
> 
> Currently this is possible by having multiple connections share a common
> interface by sharing the if_id identifier and using some other criteria
> to distinguish between them - such as different subnets or skb marks.
> This becomes complex in multi-tenant environments where subnets collide
> and the mark space is used for other purposes.
> 
> Since the xfrm interface uses the if_id as the differentiator when
> looking for policies, setting the if_id in the dst_metadata framework
> allows using a single interface for different connections while having
> the ability to selectively steer traffic to each one. In addition the
> xfrm interface "link" property can also be specified to affect underlying
> routing in the context of VRFs.
> 
> The series is composed of the following steps:
> 
> - Introduce a new METADATA_XFRM metadata type to be used for this purpose.
>   Reuse of the existing "METADATA_IP_TUNNEL" type was rejected in [0] as
>   XFRM does not necessarily represent an IP tunnel.
> 
> - Add support for collect metadata mode in xfrm interfaces
> 
> - Allow setting the XFRM metadata from the LWT infrastructure
> 
> Future additions could allow setting/getting the XFRM metadata from eBPF
> programs, TC, OVS, NF, etc.
> 
> [0] https://patchwork.kernel.org/project/netdevbpf/patch/20201121142823.3629805-1-eyal.birger@gmail.com/#23824575
> 
> Eyal Birger (3):
>   net: allow storing xfrm interface metadata in metadata_dst
>   xfrm: interface: support collect metadata mode
>   xfrm: lwtunnel: add lwtunnel support for xfrm interfaces in collect_md
>     mode
> 
>  include/net/dst_metadata.h    |  31 +++++
>  include/net/xfrm.h            |  11 +-
>  include/uapi/linux/if_link.h  |   1 +
>  include/uapi/linux/lwtunnel.h |  10 ++
>  net/core/lwtunnel.c           |   1 +
>  net/xfrm/xfrm_input.c         |   7 +-
>  net/xfrm/xfrm_interface.c     | 206 ++++++++++++++++++++++++++++++----
>  net/xfrm/xfrm_policy.c        |  10 +-
>  8 files changed, 248 insertions(+), 29 deletions(-)

Applied, thanks a lot Eyal!