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 It was superseded by series [2] by Kumar Kartikeya Dwivedi, which implements this functionality using unstable helpers.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.
[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