On Wed, 6 Feb 2019 16:37:15 -0800
Peter Oskolkov <p...@google.com> wrote:
> This patch adds all needed plumbing in preparation to allowing
> bpf programs to do IP encapping via bpf_lwt_push_encap. Actual
> implementation is added in the next patch in the patchset.
>
> Of note:
> - bpf_lwt_push_encap can now be called from BPF_PROG_TYPE_LWT_XMIT
> prog types in addition to BPF_PROG_TYPE_LWT_IN;
> - if the skb being encapped has GSO set, encapsulation is limited
> to IPIP/IP+GRE/IP+GUE (both IPv4 and IPv6);
> - as route lookups are different for ingress vs egress, the single
> external bpf_lwt_push_encap BPF helper is routed internally to
> either bpf_lwt_in_push_encap or bpf_lwt_xmit_push_encap BPF_CALLs,
> depending on prog type.
>
> Signed-off-by: Peter Oskolkov <p...@google.com>
> ---
> include/uapi/linux/bpf.h | 26 +++++++++++++++++++++--
> net/core/filter.c | 46 +++++++++++++++++++++++++++++++++++-----
> 2 files changed, 65 insertions(+), 7 deletions(-)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 1777fa0c61e4..138089ff24cf 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -2016,6 +2016,19 @@ union bpf_attr {
> * Only works if *skb* contains an IPv6 packet. Insert a
> * Segment Routing Header (**struct ipv6_sr_hdr**) inside
> * the IPv6 header.
> + * **BPF_LWT_ENCAP_IP**
> + * IP encapsulation (GRE/GUE/IPIP/etc). The outer header
> + * must be IPv4 or IPv6, followed by zero or more
> + * additional headers, up to LWT_BPF_MAX_HEADROOM total
> + * bytes in all prepended headers. PLease note that
^^
Trivial typo PLease
> + * if skb_is_gso(skb) is true, no more than two headers
> + * can be prepended, and the inner header, if present,
> + * should be either GRE or UDP/GUE.
> +
