From: Alice Mikityanska <redacted>

This series is a follow-up to "BIG TCP without HBH in IPv6", and it adds
support for BIG TCP IPv4/IPv6 workloads in vxlan and geneve. Now that
IPv6 BIG TCP doesn't require stripping the HBH in all various
combinations in tunneled traffic, adding BIG TCP becomes feasible.

Patch 01 adds accessors for the length field in the UDP header, as
suggested by Paolo in review. The usage of udp_set_len is then added in
the following patches that start using length=0 in BIG TCP UDP packets.

Patches 02-04 close the gaps that prevent BIG TCP packets from going
through UDP tunnel code.

Patch 05 validates packets in udp_gro_receive to exclude packets with
length=0 from GRO aggregation.

Patch 06 is for proper formatting in tcpdump (set UDP len to 0 rather
than a trimmed value on overflow).

Patches 07-08 bump up tso_max_size for VXLAN and GENEVE.

Patch 09 adds selftests.

Thanks all!

v9 changes: Converted the selftest to iptables counters to avoid the
issue with tcpdump pcaps taking all space in /tmp.

v8: https://lore.kernel.org/netdev/20260706181941.385672-1-alice.kernel@fastmail.im/ (local)

v8 changes: Addressed Paolo's and Jason's review comments. Made the
selftest more robust, added checks for SACK and mode with disabled tx
checksum offload on lower veth netdevs. Added details to commit
messages. Kept skb_segment logic unchanged, because the frags overflow
issue is not specific to BIG TCP.

v7: https://lore.kernel.org/netdev/20260611192955.604661-1-alice.kernel@fastmail.im/ (local)

v7 changes: Addressed Paolo's comments to properly block malformed
packets with UDP length=0 at udp_rcv level.

v6: https://lore.kernel.org/netdev/20260602093931.516281-1-alice.kernel@fastmail.im/ (local)

v6 changes: Lowered the packets threshold in the selftest to pass
upstream CI on debug kernels, also made it configurable.

v5: https://lore.kernel.org/netdev/20260526161200.1135899-1-alice.kernel@fastmail.im/ (local)

v5 changes: Rebased, dropped one of the patches that came in via the net
tree, addressed an overflow in nsim_do_psp found by Sashiko.

v4: https://lore.kernel.org/netdev/20260512165648.386518-1-alice.kernel@fastmail.im/ (local)

v4 changes: Rebased, addressed Sashiko AI review [1] and Willem's
comment about netperf flags.

My comments on Sashiko AI review per patch:

01: I'd prefer to keep the cases that I haven't tested outside of the
scope of this series, which is for VXLAN/GENEVE tunnels, not for ESP.

02: The patch doesn't have behavioral changes other than fixing the
checksum. The final uh->len assignment assigns the actual length, not
64k.

03: The check can't be loosened, because total_len is also assigned to
UDP length. BIG TCP works in the mode without GRO hint option.

04: Fixed the fallback value for udplen. BIG TCP is fine, it's the
uh->len = 0 case, uh->len can't exceed 64k.

05: In the BIG TCP case, partial GSO splits the SKB in two. If full
segmentation is needed, the SKB is split in many MSS-sized SKBs without
fragments.

06: Invalid packets from the wire are addressed in 08.

07: __udp_gso_segment only handles UDP GSO packets, which can't be
bigger than 64k. Kept udp_set_len_short in nf_nat_mangle_udp_packet, as
the function doesn't support BIG TCP packets anyway (see
mangle_contents).

08: udp_gro_receive handles packets before aggregation, there are no BIG
TCP packets at this point. RFC 768 doesn't say that padded UDP packets
are valid. Real jumbograms don't seem to be supported in this path
anyway.

09: The packet goes to skb_udp_tunnel_segment, not __udp_gso_segment.
__skb_udp_tunnel_segment handles this case.

12: Improved process cleanup by killing everything inside netns before
deleting them, and by avoiding killing netserver outside of netns.
netperf with -r in TCP_STREAM mode works, and the option has the
intended effect, but I replaced it with -m. Added dependency check for
tcpdump.

[1]: https://sashiko.dev/#/patchset/20260410150943.993350-1-alice.kernel%40fastmail.im

v3: https://lore.kernel.org/netdev/20260410150943.993350-1-alice.kernel@fastmail.im/ (local)

v3 changes: Fixed the redirect in the selftest, rebased over my L2TP fix
[2] for the syzbot report [3].

[2]: https://lore.kernel.org/netdev/20260403174949.843941-1-alice.kernel@fastmail.im/ (local)
[3]: https://lore.kernel.org/netdev/69a1dfba.050a0220.3a55be.0026.GAE@google.com/ (local)

v2: https://lore.kernel.org/netdev/20260226201600.222044-1-alice.kernel@fastmail.im/ (local)

v2 changes: Addressed the review comments: added UDP len helpers,
consolidated UDP len sanity checks in patch 08 into one, added
selftests. Added fixups to related code (patch 01-03).

v1: https://lore.kernel.org/netdev/20250923134742.1399800-1-maxtram95@gmail.com/ (local)

Alice Mikityanska (8):
  net: Use helpers to get/set UDP len tree-wide
  net: Enable BIG TCP with partial GSO
  udp: Support BIG TCP GSO packets where they can occur
  udp: Support gro_ipv4_max_size > 65536
  udp: Validate UDP length in udp_gro_receive
  udp: Set length in UDP header to 0 for big GSO packets
  vxlan: Enable BIG TCP packets
  selftests: net: Add a test for BIG TCP in UDP tunnels

Daniel Borkmann (1):
  geneve: Enable BIG TCP packets

 drivers/infiniband/core/lag.c                 |   2 +-
 drivers/infiniband/sw/rxe/rxe_net.c           |   4 +-
 drivers/net/amt.c                             |   6 +-
 drivers/net/ethernet/intel/i40e/i40e_txrx.c   |   2 +-
 drivers/net/ethernet/intel/iavf/iavf_txrx.c   |   2 +-
 drivers/net/ethernet/intel/ice/ice_txrx.c     |   2 +-
 drivers/net/ethernet/intel/idpf/idpf_txrx.c   |   2 +-
 .../marvell/octeontx2/nic/otx2_txrx.c         |   2 +-
 .../net/ethernet/mellanox/mlx5/core/en_rx.c   |   4 +-
 .../ethernet/mellanox/mlx5/core/en_selftest.c |   2 +-
 drivers/net/ethernet/sfc/falcon/selftest.c    |   4 +-
 drivers/net/ethernet/sfc/selftest.c           |   4 +-
 drivers/net/ethernet/sfc/siena/selftest.c     |   4 +-
 drivers/net/ethernet/sfc/tc_encap_actions.c   |   2 +-
 .../stmicro/stmmac/stmmac_selftests.c         |   4 +-
 drivers/net/geneve.c                          |   4 +-
 drivers/net/netconsole.c                      |   2 +-
 drivers/net/netdevsim/dev.c                   |   2 +-
 drivers/net/netdevsim/psample.c               |   2 +-
 drivers/net/netdevsim/psp.c                   |   8 +-
 drivers/net/vxlan/vxlan_core.c                |   2 +
 drivers/net/wireguard/receive.c               |   2 +-
 include/linux/udp.h                           |  27 +++
 include/trace/events/icmp.h                   |   2 +-
 lib/tests/blackhole_dev_kunit.c               |   2 +-
 net/6lowpan/nhc_udp.c                         |  10 +-
 net/core/pktgen.c                             |   4 +-
 net/core/selftests.c                          |   4 +-
 net/core/skbuff.c                             |  10 +-
 net/core/tso.c                                |   3 +-
 net/ipv4/esp4.c                               |   2 +-
 net/ipv4/fou_core.c                           |   2 +-
 net/ipv4/ipconfig.c                           |   6 +-
 net/ipv4/netfilter/nf_nat_snmp_basic_main.c   |   4 +-
 net/ipv4/route.c                              |   2 +-
 net/ipv4/udp.c                                |   7 +-
 net/ipv4/udp_offload.c                        |  49 ++---
 net/ipv4/udp_tunnel_core.c                    |   2 +-
 net/ipv6/esp6.c                               |   5 +-
 net/ipv6/fou6.c                               |   2 +-
 net/ipv6/ip6_udp_tunnel.c                     |   2 +-
 net/ipv6/udp.c                                |   7 +-
 net/ipv6/udp_offload.c                        |   2 +-
 net/l2tp/l2tp_core.c                          |   2 +-
 net/netfilter/ipvs/ip_vs_xmit.c               |   2 +-
 net/netfilter/nf_conntrack_proto_udp.c        |  15 +-
 net/netfilter/nf_log_syslog.c                 |   2 +-
 net/netfilter/nf_nat_helper.c                 |   2 +-
 net/psp/psp_main.c                            |   2 +-
 net/sched/act_csum.c                          |   4 +-
 net/xfrm/xfrm_nat_keepalive.c                 |   2 +-
 tools/testing/selftests/net/Makefile          |   1 +
 .../testing/selftests/net/big_tcp_tunnels.sh  | 188 ++++++++++++++++++
 53 files changed, 340 insertions(+), 102 deletions(-)
 create mode 100755 tools/testing/selftests/net/big_tcp_tunnels.sh

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2.54.0