[PATCH v7 bpf-next 00/10] bpf: Add socket destroy capability

[Aditi Ghag <aditi.ghag@isovalent.com>]

This patch adds the capability to destroy sockets in BPF. We plan to use
the capability in Cilium to force client sockets to reconnect when their
remote load-balancing backends are deleted. The other use case is
on-the-fly policy enforcement where existing socket connections prevented
by policies need to be terminated.

The use cases, and more details around
the selected approach were presented at LPC 2022 -
https://lpc.events/event/16/contributions/1358/.
RFC discussion -
https://lore.kernel.org/netdev/CABG=zsBEh-P4NXk23eBJw7eajB5YJeRS7oPXnTAzs=yob4EMoQ@mail.gmail.com/T/#u.
v6 patch series -
https://lore.kernel.org/bpf/20230418153148.2231644-1-aditi.ghag@isovalent.com/

v7 highlights:
Address review comments:
Martin:
- Refactored logic to get udp table to a separate commit.
- Addressed nits in the batching and test commits.
- Applied patch to filter and restrict the kfunc, and added a test.
Stan:
- Addressed nits in the network helper commit.
Paolo/Yonghong:
- Extended the first commit that revises locking in BPF TCP iterator
  with more details.
- Fixed comment formatting.

(Below notes are same as v6 patch series that are still relevant. Refer to
earlier patch series for other notes.)
- I hit a snag while writing the kfunc where verifier complained about the
  `sock_common` type passed from TCP iterator. With kfuncs, there don't
  seem to be any options available to pass BTF type hints to the verifier
  (equivalent of `ARG_PTR_TO_BTF_ID_SOCK_COMMON`, as was the case with the
  helper).  As a result, I changed the argument type of the sock_destory
  kfunc to `sock_common`.

Aditi Ghag (10):
  bpf: tcp: Avoid taking fast sock lock in iterator
  udp: seq_file: Helper function to match socket attributes
  bpf: udp: Encapsulate logic to get udp table
  udp: seq_file: Remove bpf_seq_afinfo from udp_iter_state
  bpf: udp: Implement batching for sockets iterator
  bpf: Add bpf_sock_destroy kfunc
  selftests/bpf: Add helper to get port using getsockname
  selftests/bpf: Test bpf_sock_destroy
  bpf: Add a kfunc filter function to 'struct btf_kfunc_id_set'
  selftests/bpf: Extend bpf_sock_destroy tests

 include/linux/btf.h                           |  18 +-
 include/net/udp.h                             |   1 -
 kernel/bpf/btf.c                              |  59 +++-
 kernel/bpf/verifier.c                         |   7 +-
 net/core/filter.c                             |  66 ++++
 net/ipv4/tcp.c                                |  10 +-
 net/ipv4/tcp_ipv4.c                           |   5 +-
 net/ipv4/udp.c                                | 287 +++++++++++++++---
 tools/testing/selftests/bpf/network_helpers.c |  23 ++
 tools/testing/selftests/bpf/network_helpers.h |   1 +
 .../selftests/bpf/prog_tests/sock_destroy.c   | 217 +++++++++++++
 .../selftests/bpf/progs/sock_destroy_prog.c   | 145 +++++++++
 .../bpf/progs/sock_destroy_prog_fail.c        |  22 ++
 13 files changed, 785 insertions(+), 76 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/sock_destroy.c
 create mode 100644 tools/testing/selftests/bpf/progs/sock_destroy_prog.c
 create mode 100644 tools/testing/selftests/bpf/progs/sock_destroy_prog_fail.c

-- 
2.34.1