[PATCH bpf-next v7 0/6] New BPF helpers to accelerate synproxy

Maxim Mikityanskiy
2022-04-28T15:38:50Z

The first patch of this series is an improvement to the existing
syncookie BPF helper. The second patch is a documentation fix.

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

The two last 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 It was superseded by series [2] by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 fourth patch adds new helpers to issue and check SYN cookies without
binding to a socket, which is useful in the synproxy scenario.

The fifth patch adds a selftest, which consists of a script, 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 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.

[1]: https://lore.kernel.org/bpf/20211020095815.GJ28644@breakpoint.cc/t/
[2]: https://lore.kernel.org/bpf/20220114163953.1455836-1-memxor@gmail.com/
[3]: https://netdevconf.info/0x15/session.html?Accelerating-synproxy-with-XDP

Maxim Mikityanskiy (6):
bpf: Use ipv6_only_sock in bpf_tcp_gen_syncookie
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 | 130 ++-
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, 1760 insertions(+), 22 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

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2.30.2