[PATCH ipsec-next v3 0/9] Add bpf_xdp_get_xfrm_state() kfunc

Daniel Xu
2023-12-01T20:23:56Z

This patchset adds two kfunc helpers, bpf_xdp_get_xfrm_state() and
bpf_xdp_xfrm_state_release() that wrap xfrm_state_lookup() and
xfrm_state_put(). The intent is to support software RSS (via XDP) for
the ongoing/upcoming ipsec pcpu work [0]. Recent experiments performed
on (hopefully) reproducible AWS testbeds indicate that single tunnel
pcpu ipsec can reach line rate on 100G ENA nics.

Note this patchset only tests/shows generic xfrm_state access. The
"secret sauce" (if you can really even call it that) involves accessing
a soon-to-be-upstreamed pcpu_num field in xfrm_state. Early example is
available here [1].

[0]: https://datatracker.ietf.org/doc/draft-ietf-ipsecme-multi-sa-performance/03/
[1]: https://github.com/danobi/xdp-tools/blob/e89a1c617aba3b50d990f779357d6ce2863ecb27/xdp-bench/xdp_redirect_cpumap.bpf.c#L385-L406

Changes from v2:
* Fix/simplify BPF_CORE_WRITE_BITFIELD() algorithm
* Added verifier tests for bitfield writes
* Fix state leakage across test_tunnel subtests

Changes from v1:
* Move xfrm tunnel tests to test_progs
* Fix writing to opts->error when opts is invalid
* Use __bpf_kfunc_start_defs()
* Remove unused vxlanhdr definition
* Add and use BPF_CORE_WRITE_BITFIELD() macro
* Make series bisect clean

Changes from RFCv2:
* Rebased to ipsec-next
* Fix netns leak

Changes from RFCv1:
* Add Antony's commit tags
* Add KF_ACQUIRE and KF_RELEASE semantics

Daniel Xu (9):
bpf: xfrm: Add bpf_xdp_get_xfrm_state() kfunc
bpf: xfrm: Add bpf_xdp_xfrm_state_release() kfunc
libbpf: Add BPF_CORE_WRITE_BITFIELD() macro
bpf: selftests: test_loader: Support __btf_path() annotation
libbpf: selftests: Add verifier tests for CO-RE bitfield writes
bpf: selftests: test_tunnel: Setup fresh topology for each subtest
bpf: selftests: test_tunnel: Use vmlinux.h declarations
bpf: selftests: Move xfrm tunnel test to test_progs
bpf: xfrm: Add selftest for bpf_xdp_get_xfrm_state()

include/net/xfrm.h | 9 +
net/xfrm/Makefile | 1 +
net/xfrm/xfrm_policy.c | 2 +
net/xfrm/xfrm_state_bpf.c | 128 ++++++++++++++
tools/lib/bpf/bpf_core_read.h | 34 ++++
.../selftests/bpf/prog_tests/test_tunnel.c | 162 +++++++++++++++++-
.../selftests/bpf/prog_tests/verifier.c | 2 +
tools/testing/selftests/bpf/progs/bpf_misc.h | 1 +
.../selftests/bpf/progs/bpf_tracing_net.h | 1 +
.../selftests/bpf/progs/test_tunnel_kern.c | 138 ++++++++-------
.../bpf/progs/verifier_bitfield_write.c | 100 +++++++++++
tools/testing/selftests/bpf/test_loader.c | 7 +
tools/testing/selftests/bpf/test_tunnel.sh | 92 ----------
13 files changed, 522 insertions(+), 155 deletions(-)
create mode 100644 net/xfrm/xfrm_state_bpf.c
create mode 100644 tools/testing/selftests/bpf/progs/verifier_bitfield_write.c

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2.42.1