[PATCH bpf v9 0/5] bpf: fix wrong copied_seq calculation and add tests

Jiayuan Chen
2025-01-22T10:11:31Z

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 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/
Fixed some issues suggested by Jakub Sitnicki.

V7 -> V8
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 | 36 ++
net/strparser/strparser.c | 11 +-
.../selftests/bpf/prog_tests/sockmap_basic.c | 59 +--
.../selftests/bpf/prog_tests/sockmap_strp.c | 454 ++++++++++++++++++
.../selftests/bpf/progs/test_sockmap_strp.c | 53 ++
12 files changed, 610 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

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2.43.5