[PATCH v5 bpf-next 0/7] bpf: Add socket destroy capability

Aditi Ghag
2023-03-30T15:19:41Z

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.
v4 patch series -
https://lore.kernel.org/bpf/20230323200633.3175753-1-aditi.ghag@isovalent.com/T/#t

v5 highlights:
Address review comments:
Martin:
- Fixed bugs in the resume operation for UDP iterator.
- Added clean-up preparatory commits prior to the batching commit.
Stan:
- Programmatically retrieve and share server port in the selftests.
- Acquire slow sock lock in UDP iterator to be consistent with TCP.
- Addressed formatting nits.

(Below notes are same as v2 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 (7):
bpf: tcp: Avoid taking fast sock lock in iterator
udp: seq_file: Remove bpf_seq_afinfo from udp_iter_state
udp: seq_file: Helper function to match socket attributes
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

include/net/udp.h | 1 -
net/core/filter.c | 54 ++++
net/ipv4/tcp.c | 10 +-
net/ipv4/tcp_ipv4.c | 5 +-
net/ipv4/udp.c | 286 +++++++++++++++---
tools/testing/selftests/bpf/network_helpers.c | 14 +
tools/testing/selftests/bpf/network_helpers.h | 1 +
.../selftests/bpf/prog_tests/sock_destroy.c | 203 +++++++++++++
.../selftests/bpf/progs/sock_destroy_prog.c | 147 +++++++++
9 files changed, 676 insertions(+), 45 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

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2.34.1