On Tue, 05 May 2026 01:30:15 +0900 Yuya Kusakabe <[email protected]> wrote:
Hi Yuya, I do not repeat below the points from the cover letter thread and patch 1-4 replies (drop reasons, OIF/VRF removal, C helper, coding style, etc.). The patch 4 review applies here, except for the parts where Section 6.4 is implemented instead of Section 6.3 (which is incorrectly implemented in patch 4). > Add the End.M.GTP6.D.Di drop-in mode variant of End.M.GTP6.D > (RFC 9433 Section 6.4). Unlike End.M.GTP6.D, the drop-in variant > does NOT fold the GTP-U identifiers into Args.Mob.Session: the > original outer IPv6 destination is preserved at SRH[0] of the new > SRH, so the destination side can keep the original address > untouched while still benefiting from SR Policy steering. > > The augmented SRH builder/destroyer is shared with End.M.GTP6.D. > The TEID and QFI parsed out of the inbound GTP-U header are > intentionally discarded for this variant (matching RFC 9433 > Section 6.4). > > When net.netfilter.nf_hooks_lwtunnel=1, the inner T-PDU traverses > NF_INET_PRE_ROUTING between the GTP-U strip and the SRv6 push, > mirroring End.DX4 / End.DX6. > > Non-T-PDU GTP-U messages are forwarded the same way as in > End.M.GTP6.D: passed through via the lwtunnel's saved orig_input > to a downstream peer that owns the GTP-U control plane. > > Configuration: > > ip -6 route add 2001:db8:f::/64 \ > encap seg6local action End.M.GTP6.D.Di \ > srh segs 2001:db8:2::e,2001:db8:3::e \ > src 2001:db8:2::1 \ > dev <dev> > > Link: https://www.rfc-editor.org/rfc/rfc9433.html#section-6.4 > Signed-off-by: Yuya Kusakabe <[email protected]> > --- > include/uapi/linux/seg6_local.h | 2 + > net/ipv6/seg6_local.c | 222 +++++++++++ > tools/testing/selftests/net/Makefile | 1 + > .../selftests/net/srv6_end_m_gtp6_d_di_test.sh | 427 > +++++++++++++++++++++ > 4 files changed, 652 insertions(+) > > diff --git a/include/uapi/linux/seg6_local.h b/include/uapi/linux/seg6_local.h > index 7d3d3d245b47..326da65ad5aa 100644 > --- a/include/uapi/linux/seg6_local.h > +++ b/include/uapi/linux/seg6_local.h > @@ -80,6 +80,8 @@ enum { > SEG6_LOCAL_ACTION_END_M_GTP6_E = 19, > /* IPv6/GTP-U decap into SRv6 (RFC 9433 Section 6.3) */ > SEG6_LOCAL_ACTION_END_M_GTP6_D = 20, > + /* IPv6/GTP-U decap into SRv6, drop-in mode (RFC 9433 Section 6.4) */ > + SEG6_LOCAL_ACTION_END_M_GTP6_D_DI = 21, > > __SEG6_LOCAL_ACTION_MAX, > }; > diff --git a/net/ipv6/seg6_local.c b/net/ipv6/seg6_local.c > index 09e912e17df8..a6cd57ebcbde 100644 > --- a/net/ipv6/seg6_local.c > +++ b/net/ipv6/seg6_local.c > + [snip] input_action_end_m_gtp6_d_di() and its finish callback are largely identical to the patch 4 functions (input_action_end_m_gtp6_d() and its finish): the SRH check, GTP-U dispatch, outer strip, inner protocol detection, and NF_HOOK invocation are identical. The duplication should be reduced via shared helpers. > +static int input_action_end_m_gtp6_d_di(struct sk_buff *skb, > + struct seg6_local_lwt *slwt) > +{ > + [snip] > + gtp_hdrlen = seg6_mobile_parse_gtpu(skb, > + upper_off + sizeof(*uh), > + &teid, &qfi); > + if (gtp_hdrlen == -EOPNOTSUPP) > + return seg6_mobile_passthrough_non_tpdu(skb); > + if (gtp_hdrlen < 0) { > + reason = SKB_DROP_REASON_SEG6_MOBILE_BAD_GTPU; > + goto drop; > + } > + (void)teid; > + (void)qfi; D.Di does not use teid or qfi, so these variables and the (void) casts are dead code and should be avoided. For example, seg6_mobile_parse_gtpu() could accept NULL for teid and qfi so callers that do not need them can pass NULL directly. Thanks, Ciao, Andrea P.S. I am temporarily writing from another address due to a mail delivery issue at my @uniroma2.it address. Please always Cc my default [email protected] address on replies.
