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 was 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. v2 patch series - https://lore.kernel.org/bpf/20230223215311.926899-1-aditi.ghag@xxxxxxxxxxxxx/T/#t v4 highlights: - Updated locking in BPF TCP iterator. - Adapted *-server selftests similar to the client selftests per the discussions. - Addressed Stan's comment to revert skipping spin locks in tcp_abort. - Dropped the fix to unhash UDP sockets during abort. - Moved the iterator resume related changes to the right commit. (Below notes are same as last patch series.) - 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 (4): bpf: Implement batching in UDP iterator bpf: Add bpf_sock_destroy kfunc bpf,tcp: Avoid taking fast sock lock in iterator selftests/bpf: Add tests for 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 | 261 +++++++++++++++++- .../selftests/bpf/prog_tests/sock_destroy.c | 195 +++++++++++++ .../selftests/bpf/progs/sock_destroy_prog.c | 151 ++++++++++ 7 files changed, 660 insertions(+), 17 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
