On Wed, Jan 22, 2025 at 06:09 PM +08, Jiayuan Chen wrote:

A previous commit described in this topic
http://lore.kernel.org/bpf/20230523025618.113937-9-john.fastabend@gmail.com (local)
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 updates '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.

---
V8 -> v9
https://lore.kernel.org/bpf/20250121050707.55523-1-mrpre@163.com/ (local)
Fixed some issues suggested by Jakub Sitnicki.

V7 -> V8
https://lore.kernel.org/bpf/20250116140531.108636-1-mrpre@163.com/ (local)
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/ (local)
https://lore.kernel.org/bpf/20241218053408.437295-1-mrpre@163.com/ (local)
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/ (local)
Fix patchwork fail by adding Fixes tag.
Save skb data offset for ENOMEM. (John Fastabend)
---

Thanks for addressing all feedback, Jiayuan. Series LGTM.
Feel free to carry my tags if there is another iteration.

-jkbs