A previous commit described in this topic http://lore.kernel.org/bpf/20230523025618.113937-9-john.fastabend@gmail.com directly updated 'sk->copied_seq' in the tcp_eat_skb() function when the action of a BPF program was SK_REDIRECT. For other actions, like SK_PASS, the update logic for 'sk->copied_seq' was moved to tcp_bpf_recvmsg_parser() to ensure the accuracy of the 'fionread' feature.
That commit works for a single stream_verdict scenario, as it also modified 'sk_data_ready->sk_psock_verdict_data_ready->tcp_read_skb' to remove updating 'sk->copied_seq'.
However, for programs where both stream_parser and stream_verdict are active(strparser purpose), tcp_read_sock() was used instead of tcp_read_skb() (sk_data_ready->strp_data_ready->tcp_read_sock) tcp_read_sock() now still update 'sk->copied_seq', leading to duplicated updates.
In summary, for strparser + SK_PASS, copied_seq is redundantly calculated in both tcp_read_sock() and tcp_bpf_recvmsg_parser().
The issue causes incorrect copied_seq calculations, which prevent correct data reads from the recv() interface in user-land.
Also we added test cases for bpf + strparser and separated them from sockmap_basic, as strparser has more encapsulation and parsing capabilities compared to sockmap.
Fixes: e5c6de5fa025 ("bpf, sockmap: Incorrectly handling copied_seq")
--- V8 -> V7: https://lore.kernel.org/bpf/20250116140531.108636-1-mrpre@163.com/ Avoid using add read_sock to psock. (Jakub Sitnicki) Avoid using warpper function to check whether strparser is supported.
V3 -> V7: https://lore.kernel.org/bpf/20250109094402.50838-1-mrpre@163.com/ https://lore.kernel.org/bpf/20241218053408.437295-1-mrpre@163.com/ Avoid introducing new proto_ops. (Jakub Sitnicki). Add more edge test cases for strparser + bpf. Fix patchwork fail of test cases code. Fix psock fetch without rcu lock. Move code of modifying to tcp_bpf.c.
V1 -> V3: https://lore.kernel.org/bpf/20241209152740.281125-1-mrpre@163.com/ Fix patchwork fail by adding Fixes tag. Save skb data offset for ENOMEM. (John Fastabend) ---
Jiayuan Chen (5): strparser: add read_sock callback bpf: fix wrong copied_seq calculation bpf: disable non stream socket for strparser selftests/bpf: fix invalid flag of recv() selftests/bpf: add strparser test for bpf
Documentation/networking/strparser.rst | 9 +- include/linux/skmsg.h | 2 + include/net/strparser.h | 2 + include/net/tcp.h | 8 + net/core/skmsg.c | 7 + net/core/sock_map.c | 5 +- net/ipv4/tcp.c | 29 +- net/ipv4/tcp_bpf.c | 42 ++ net/strparser/strparser.c | 11 +- .../selftests/bpf/prog_tests/sockmap_basic.c | 59 +-- .../selftests/bpf/prog_tests/sockmap_strp.c | 452 ++++++++++++++++++ .../selftests/bpf/progs/test_sockmap_strp.c | 53 ++ 12 files changed, 614 insertions(+), 65 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/sockmap_strp.c create mode 100644 tools/testing/selftests/bpf/progs/test_sockmap_strp.c