[PATCH bpf-next v4 0/7] Add SO_REUSEPORT support for TC bpf_sk_assign

[Lorenz Bauer]

We want to replace iptables TPROXY with a BPF program at TC ingress.
To make this work in all cases we need to assign a SO_REUSEPORT socket
to an skb, which is currently prohibited. This series adds support for
such sockets to bpf_sk_assing.

I did some refactoring to cut down on the amount of duplicate code. The
key to this is to use INDIRECT_CALL in the reuseport helpers. To show
that this approach is not just beneficial to TC sk_assign I removed
duplicate code for bpf_sk_lookup as well.

Joint work with Daniel Borkmann.

Signed-off-by: Lorenz Bauer <lmb@xxxxxxxxxxxxx>
---
Changes in v4:
- WARN_ON_ONCE if reuseport socket is refcounted (Kuniyuki)
- Use inet[6]_ehashfn_t to shorten function declarations (Kuniyuki)
- Shuffle documentation patch around (Kuniyuki)
- Update commit message to explain why IPv6 needs EXPORT_SYMBOL
- Link to v3: https://lore.kernel.org/r/20230613-so-reuseport-v3-0-907b4cbb7b99@xxxxxxxxxxxxx

Changes in v3:
- Fix warning re udp_ehashfn and udp6_ehashfn (Simon)
- Return higher scoring connected UDP reuseport sockets (Kuniyuki)
- Fix ipv6 module builds
- Link to v2: https://lore.kernel.org/r/20230613-so-reuseport-v2-0-b7c69a342613@xxxxxxxxxxxxx

Changes in v2:
- Correct commit abbrev length (Kuniyuki)
- Reduce duplication (Kuniyuki)
- Add checks on sk_state (Martin)
- Split exporting inet[6]_lookup_reuseport into separate patch (Eric)

---
Daniel Borkmann (1):
      selftests/bpf: Test that SO_REUSEPORT can be used with sk_assign helper

Lorenz Bauer (6):
      udp: re-score reuseport groups when connected sockets are present
      net: export inet_lookup_reuseport and inet6_lookup_reuseport
      net: remove duplicate reuseport_lookup functions
      net: document inet[6]_lookup_reuseport sk_state requirements
      net: remove duplicate sk_lookup helpers
      bpf, net: Support SO_REUSEPORT sockets with bpf_sk_assign

 include/net/inet6_hashtables.h                     |  81 ++++++++-
 include/net/inet_hashtables.h                      |  74 +++++++-
 include/net/sock.h                                 |   7 +-
 include/uapi/linux/bpf.h                           |   3 -
 net/core/filter.c                                  |   2 -
 net/ipv4/inet_hashtables.c                         |  67 ++++---
 net/ipv4/udp.c                                     |  88 ++++-----
 net/ipv6/inet6_hashtables.c                        |  70 +++++---
 net/ipv6/udp.c                                     |  98 ++++------
 tools/include/uapi/linux/bpf.h                     |   3 -
 tools/testing/selftests/bpf/network_helpers.c      |   3 +
 .../selftests/bpf/prog_tests/assign_reuse.c        | 197 +++++++++++++++++++++
 .../selftests/bpf/progs/test_assign_reuse.c        | 142 +++++++++++++++
 13 files changed, 656 insertions(+), 179 deletions(-)
---
base-commit: 970308a7b544fa1c7ee98a2721faba3765be8dd8
change-id: 20230613-so-reuseport-e92c526173ee

Best regards,
-- 
Lorenz Bauer <lmb@xxxxxxxxxxxxx>