[bpf-next,v8,0/5] New BPF helpers to accelerate synproxy

Message

Maxim Mikityanskiy April 29, 2022, 11:15 a.m. UTC

The first patch of this series is a documentation fix.

The second patch allows BPF helpers to accept memory regions of fixed
size without doing runtime size checks.

The two next patches add new functionality that allows XDP to
accelerate iptables synproxy.

v1 of this series [1] used to include a patch that exposed conntrack
lookup to BPF using stable helpers. It was superseded by series [2] by
Kumar Kartikeya Dwivedi, which implements this functionality using
unstable helpers.

The third patch adds new helpers to issue and check SYN cookies without
binding to a socket, which is useful in the synproxy scenario.

The fourth patch adds a selftest, which includes an XDP program and a
userspace control application. The XDP program uses socketless SYN
cookie helpers and queries conntrack status instead of socket status.
The userspace control application allows to tune parameters of the XDP
program. This program also serves as a minimal example of usage of the
new functionality.

The last patch exposes the new helpers to TC BPF.

The draft of the new functionality was presented on Netdev 0x15 [3].

v2 changes:

Split into two series, submitted bugfixes to bpf, dropped the conntrack
patches, implemented the timestamp cookie in BPF using bpf_loop, dropped
the timestamp cookie patch.

v3 changes:

Moved some patches from bpf to bpf-next, dropped the patch that changed
error codes, split the new helpers into IPv4/IPv6, added verifier
functionality to accept memory regions of fixed size.

v4 changes:

Converted the selftest to the test_progs runner. Replaced some
deprecated functions in xdp_synproxy userspace helper.

v5 changes:

Fixed a bug in the selftest. Added questionable functionality to support
new helpers in TC BPF, added selftests for it.

v6 changes:

Wrap the new helpers themselves into #ifdef CONFIG_SYN_COOKIES, replaced
fclose with pclose and fixed the MSS for IPv6 in the selftest.

v7 changes:

Fixed the off-by-one error in indices, changed the section name to
"xdp", added missing kernel config options to vmtest in CI.

v8 changes:

Properly rebased, dropped the first patch (the same change was applied
by someone else), updated the cover letter.

[1]: https://lore.kernel.org/bpf/[e-mail]/t/
[2]: https://lore.kernel.org/bpf/[e-mail]/
[3]: https://netdevconf.info/0x15/session.html?Accelerating-synproxy-with-XDP

Maxim Mikityanskiy (5):
  bpf: Fix documentation of th_len in bpf_tcp_{gen,check}_syncookie
  bpf: Allow helpers to accept pointers with a fixed size
  bpf: Add helpers to issue and check SYN cookies in XDP
  bpf: Add selftests for raw syncookie helpers
  bpf: Allow the new syncookie helpers to work with SKBs

 include/linux/bpf.h                           |  10 +
 include/net/tcp.h                             |   1 +
 include/uapi/linux/bpf.h                      |  88 +-
 kernel/bpf/verifier.c                         |  26 +-
 net/core/filter.c                             | 128 +++
 net/ipv4/tcp_input.c                          |   3 +-
 scripts/bpf_doc.py                            |   4 +
 tools/include/uapi/linux/bpf.h                |  88 +-
 tools/testing/selftests/bpf/.gitignore        |   1 +
 tools/testing/selftests/bpf/Makefile          |   2 +-
 .../selftests/bpf/prog_tests/xdp_synproxy.c   | 144 +++
 .../selftests/bpf/progs/xdp_synproxy_kern.c   | 819 ++++++++++++++++++
 tools/testing/selftests/bpf/xdp_synproxy.c    | 466 ++++++++++
 13 files changed, 1759 insertions(+), 21 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_synproxy.c
 create mode 100644 tools/testing/selftests/bpf/progs/xdp_synproxy_kern.c
 create mode 100644 tools/testing/selftests/bpf/xdp_synproxy.c