[bpf,v8,0/5] bpf: fix wrong copied_seq calculation and add tests

Message

Jiayuan Chen Jan. 21, 2025, 5:07 a.m. UTC

A previous commit described in this topic
http://lore.kernel.org/bpf/[e-mail]
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/[e-mail]/
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/[e-mail]/
https://lore.kernel.org/bpf/[e-mail]/
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/[e-mail]/
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