Hi Daniel, On Wed, Aug 24, 2022 at 8:06 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote: > > Hi Eyal, > > On 8/23/22 5:45 PM, Eyal Birger wrote: > > This commit adds support for 'collect_md' mode on xfrm interfaces. > > > > Each net can have one collect_md device, created by providing the > > IFLA_XFRM_COLLECT_METADATA flag at creation. This device cannot be > > altered and has no if_id or link device attributes. > > > > On transmit to this device, the if_id is fetched from the attached dst > > metadata on the skb. The dst metadata type used is METADATA_XFRM > > which holds the if_id property. > > > > On the receive side, xfrmi_rcv_cb() populates a dst metadata for each > > packet received and attaches it to the skb. The if_id used in this case is > > fetched from the xfrm state. This can later be used by upper layers such > > as tc, ebpf, and ip rules. > > > > Because the skb is scrubed in xfrmi_rcv_cb(), the attachment of the dst > > metadata is postponed until after scrubing. Similarly, xfrm_input() is > > adapted to avoid dropping metadata dsts by only dropping 'valid' > > (skb_valid_dst(skb) == true) dsts. > > > > Policy matching on packets arriving from collect_md xfrmi devices is > > done by using the xfrm state existing in the skb's sec_path. > > The xfrm_if_cb.decode_cb() interface implemented by xfrmi_decode_session() > > is changed to keep the details of the if_id extraction tucked away > > in xfrm_interface.c. > > > > Signed-off-by: Eyal Birger <eyal.birger@xxxxxxxxx> > > Can be done in follow-up (once merged back from net-next into bpf-next), > but it would be nice to also have a BPF CI selftest for it to make sure > the ipsec+collect_md with BPF is consistently tested for incoming patches. Indeed. Note that this requires the addition of set/get bpf helpers for this metadata as the existing helpers are tied to ip_tunnel_info. I used such helpers as part of testing this patch series, and plan to submit them with the respective tests to bpf-next once this feature is merged in its final form. Thanks! Eyal
