[PATCH v6 nf-next 0/3] ipvs: add per-service secure_tcp

[Adriano Cordova <adrianox@gmail.com>]

IPVS currently exposes secure_tcp as a per-netns sysctl. It switches the
TCP state machine to the hardened tcp_states_dos table.

These patches make it per-service: a virtual service can set
IP_VS_SVC_F_SECURE_TCP which is passed into IP_VS_CONN_F_SECURE_TCP at
connection creation. set_tcp_state() then selects tcp_states_dos for those
connections with IP_VS_CONN_F_SECURE_TCP set and keeps pd->tcp_state_table
(the netns default, including the nomem floor) otherwise.

  1. uapi: define the per-service secure_tcp flags and stamp the flag in
     ip_vs_bind_dest() (cache-bypass has no dest)
  2. honor it in the TCP state machine, resolving the stale FIXME, and
     document the new default/opt-in split
  3. kselftest contrasting a secure vs. a plain service

Changes in v2:
- Let IP_VS_SVC_F_SECURE_TCP be 0x0100, leaving 0x0040/0x0080 for the
  scheduler flags. Let IP_VS_CONN_F_SECURE_TCP be (1 << 17) and no longer
  in IP_VS_CONN_F_BACKUP_MASK.
- Set flag in ip_vs_bind_dest() instead of at every ip_vs_conn_new()
  call site.
- selftest: send probes with TTL=1 instead of an nft drop, and fix
  Sashiko comments.

Changes in v3:
- Merge patch 1/4 and 2/4
- Re-send patches (v2 dropped patches 3/4 and 4/4)

Changes in v4:
- selftest: check the return values of setsockopt(IP_HDRINCL), sendto()
  and mnl_socket_bind(), and fail do_add() when IPVS does not reply.
- selftest: fix the remaining Sashiko comments: check inet_pton(),
  initialize fam and the parsed addresses, and verify the flags attribute
  length before copying it.

Changes in v5:
- Document secure_tcp as the netns-wide default and the new per-service
  IP_VS_SVC_F_SECURE_TCP opt-in.
- selftest: reword the changelog to "a bare SYN followed by a bare ACK".
- selftest: skip when the ip_vs or ip_vs_rr module is unavailable.
- selftest: check the probe exit status so that a probe which dies after
  the SYN cannot leave the secure-side SYN_RECV assertion passing.

Changes in v6:
- Rebase onto nf-next.

Adriano Cordova (3):
  ipvs: add flags for per-service secure TCP state table
  ipvs: tcp: enable per-connection secure_tcp in state machine
  selftests: netfilter: ipvs: add per-service secure_tcp test

 Documentation/networking/ipvs-sysctl.rst      |   4 +
 include/uapi/linux/ip_vs.h                    |   2 +
 net/netfilter/ipvs/ip_vs_conn.c               |   4 +
 net/netfilter/ipvs/ip_vs_core.c               |   3 +
 net/netfilter/ipvs/ip_vs_proto_tcp.c          |  16 +-
 .../testing/selftests/net/netfilter/Makefile  |   6 +
 .../selftests/net/netfilter/gen_tcp_probe.c   | 158 ++++++++
 .../net/netfilter/ipvs_secure_tcp.sh          | 169 +++++++++
 .../net/netfilter/ipvs_secure_tcp_mln.c       | 337 ++++++++++++++++++
 9 files changed, 692 insertions(+), 7 deletions(-)
 create mode 100644 tools/testing/selftests/net/netfilter/gen_tcp_probe.c
 create mode 100755 tools/testing/selftests/net/netfilter/ipvs_secure_tcp.sh
 create mode 100644 tools/testing/selftests/net/netfilter/ipvs_secure_tcp_mln.c


base-commit: 8b4e7209c842d8cb9516f1f5ef0a88aa2d8831a6
-- 
2.51.0