Re: [PATCH bpf-next v7 00/13] New nf_conntrack kfuncs for insertion, changing timeout, status

[Zvi Effron <zeffron@riotgames.com>]

On Thu, Jul 21, 2022 at 6:43 AM Kumar Kartikeya Dwivedi
<memxor@gmail.com> wrote:
>
> Introduce the following new kfuncs:
> - bpf_{xdp,skb}_ct_alloc
> - bpf_ct_insert_entry
> - bpf_ct_{set,change}_timeout
> - bpf_ct_{set,change}_status
>
> The setting of timeout and status on allocated or inserted/looked up CT
> is same as the ctnetlink interface, hence code is refactored and shared
> with the kfuncs. It is ensured allocated CT cannot be passed to kfuncs
> that expected inserted CT, and vice versa. Please see individual patches
> for details.
>

Is it expected that using these helpers and the kernel's conntrack to manage
connection state from XDP will outperform using maps and eBPF timers (for XDP
use cases that don't have a userspace component that also needs the information
in conntrack)? Have you done any benchmarking on the performance of using
conntrack from XDP?

Thanks!
--Zvi

> Changelog:
> ----------
> v6 -> v7:
> v6: https://lore.kernel.org/bpf/20220719132430.19993-1-memxor@gmail.com
>
> * Use .long to encode flags (Alexei)
> * Fix description of KF_RET_NULL in documentation (Toke)
>
> v5 -> v6:
> v5: https://lore.kernel.org/bpf/20220623192637.3866852-1-memxor@gmail.com
>
> * Introduce kfunc flags, rework verifier to work with them
> * Add documentation for kfuncs
> * Add comment explaining TRUSTED_ARGS kfunc flag (Alexei)
> * Fix missing offset check for trusted arguments (Alexei)
> * Change nf_conntrack test minimum delta value to 8
>
> v4 -> v5:
> v4: https://lore.kernel.org/bpf/cover.1653600577.git.lorenzo@kernel.org
>
> * Drop read-only PTR_TO_BTF_ID approach, use struct nf_conn___init (Alexei)
> * Drop acquire release pair code that is no longer required (Alexei)
> * Disable writes into nf_conn, use dedicated helpers (Florian, Alexei)
> * Refactor and share ctnetlink code for setting timeout and status
> * Do strict type matching on finding __ref suffix on argument to
> prevent passing nf_conn___init as nf_conn (offset = 0, match on walk)
> * Remove bpf_ct_opts parameter from bpf_ct_insert_entry
> * Update selftests for new additions, add more negative tests
>
> v3 -> v4:
> v3: https://lore.kernel.org/bpf/cover.1652870182.git.lorenzo@kernel.org
>
> * split bpf_xdp_ct_add in bpf_xdp_ct_alloc/bpf_skb_ct_alloc and
> bpf_ct_insert_entry
> * add verifier code to properly populate/configure ct entry
> * improve selftests
>
> v2 -> v3:
> v2: https://lore.kernel.org/bpf/cover.1652372970.git.lorenzo@kernel.org
>
> * add bpf_xdp_ct_add and bpf_ct_refresh_timeout kfunc helpers
> * remove conntrack dependency from selftests
> * add support for forcing kfunc args to be referenced and related selftests
>
> v1 -> v2:
> v1: https://lore.kernel.org/bpf/1327f8f5696ff2bc60400e8f3b79047914ccc837.1651595019.git.lorenzo@kernel.org
>
> * add bpf_ct_refresh_timeout kfunc selftest
>
> Kumar Kartikeya Dwivedi (10):
> bpf: Introduce 8-byte BTF set
> tools/resolve_btfids: Add support for 8-byte BTF sets
> bpf: Switch to new kfunc flags infrastructure
> bpf: Add support for forcing kfunc args to be trusted
> bpf: Add documentation for kfuncs
> net: netfilter: Deduplicate code in bpf_{xdp,skb}_ct_lookup
> net: netfilter: Add kfuncs to set and change CT timeout
> selftests/bpf: Add verifier tests for trusted kfunc args
> selftests/bpf: Add negative tests for new nf_conntrack kfuncs
> selftests/bpf: Fix test_verifier failed test in unprivileged mode
>
> Lorenzo Bianconi (3):
> net: netfilter: Add kfuncs to allocate and insert CT
> net: netfilter: Add kfuncs to set and change CT status
> selftests/bpf: Add tests for new nf_conntrack kfuncs
>
> Documentation/bpf/index.rst | 1 +
> Documentation/bpf/kfuncs.rst | 170 ++++++++
> include/linux/bpf.h | 3 +-
> include/linux/btf.h | 65 ++--
> include/linux/btf_ids.h | 68 +++-
> include/net/netfilter/nf_conntrack_core.h | 19 +
> kernel/bpf/btf.c | 123 +++---
> kernel/bpf/verifier.c | 14 +-
> net/bpf/test_run.c | 75 ++--
> net/ipv4/bpf_tcp_ca.c | 18 +-
> net/ipv4/tcp_bbr.c | 24 +-
> net/ipv4/tcp_cubic.c | 20 +-
> net/ipv4/tcp_dctcp.c | 20 +-
> net/netfilter/nf_conntrack_bpf.c | 365 +++++++++++++-----
> net/netfilter/nf_conntrack_core.c | 62 +++
> net/netfilter/nf_conntrack_netlink.c | 54 +--
> tools/bpf/resolve_btfids/main.c | 40 +-
> .../selftests/bpf/bpf_testmod/bpf_testmod.c | 10 +-
> .../testing/selftests/bpf/prog_tests/bpf_nf.c | 64 ++-
> .../testing/selftests/bpf/progs/test_bpf_nf.c | 85 +++-
> .../selftests/bpf/progs/test_bpf_nf_fail.c | 134 +++++++
> .../selftests/bpf/verifier/bpf_loop_inline.c | 1 +
> tools/testing/selftests/bpf/verifier/calls.c | 53 +++
> 23 files changed, 1139 insertions(+), 349 deletions(-)
> create mode 100644 Documentation/bpf/kfuncs.rst
> create mode 100644 tools/testing/selftests/bpf/progs/test_bpf_nf_fail.c
>
> --
> 2.34.1
>