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. v6 patch series - https://lore.kernel.org/bpf/20230418153148.2231644-1-aditi.ghag@xxxxxxxxxxxxx/ 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
