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@xxxxxxxxxxxxxx/T/#u. v5 patch series - https://lore.kernel.org/bpf/20230330151758.531170-1-aditi.ghag@xxxxxxxxxxxxx/ v6 highlights: Address review comments: Martin: - Simplified UDP batching iterator logic. - Run tests in a separate netns. Stan: - Make destroy handler checks opt-in. - Extended network helper to get socket port for v4. kernel test robot: - Updated seq_sk_match and seq_file_family with the necessary ifdefs. (Below notes are same as v5 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`. - Martin's patch restricts the helper to only BPF iterators - https://lore.kernel.org/bpf/20230404060959.2259448-1-martin.lau@xxxxxxxxx/. Applied, and tested the patch locally. 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 | 57 ++++ net/ipv4/tcp.c | 10 +- net/ipv4/tcp_ipv4.c | 5 +- net/ipv4/udp.c | 269 +++++++++++++++--- tools/testing/selftests/bpf/network_helpers.c | 28 ++ tools/testing/selftests/bpf/network_helpers.h | 1 + .../selftests/bpf/prog_tests/sock_destroy.c | 217 ++++++++++++++ .../selftests/bpf/progs/sock_destroy_prog.c | 147 ++++++++++ 9 files changed, 690 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 -- 2.34.1
