[PATCH net v2 0/2] net: tls: fix async split record handling

[Christopher Lusk <clusk@northecho.dev>]

When BPF sk_msg apply_bytes splits an open kTLS TX record and the
selected AEAD provider completes asynchronously, tls_push_record()
currently returns -EINPROGRESS before reattaching the split remainder.
The peer can receive a truncated stream and the detached tls_rec
remainder is leaked.

Patch 1 keeps the split remainder rooted before returning
-EINPROGRESS, continues the BPF verdict drain loop after queueing an
async record, and waits for already-queued async encryption if a later
verdict iteration must return a hard error. That last part addresses
the return-value masking issue reported by Sashiko on v1.

Patch 2 adds a selftest covering the sync and async providers for the
split-record path. v2 also checks the BPF program fd before attaching
the selftest program.

This report and patch were prepared with AI assistance. The generated
analysis was checked against the current source, the reproducer was run
against vulnerable and fixed kernels, and the fix was runtime-validated
on QEMU/KVM with a KASAN+LOCKDEP-instrumented kernel against net base
5db89c995. The pass-then-drop BPF probe that exercises Finding 1's
failure mode ran clean (no KASAN report, no lockdep splat).

v1:
https://lore.kernel.org/all/20260515151556.189841-1-clusk@northecho.dev/

Sashiko review:
https://sashiko.dev/#/patchset/20260515151556.189841-1-clusk@northecho.dev

John Fastabend reply on v1 (confirmed Sashiko's return-value masking
finding is a legitimate concern; this v2 is the response):
https://lore.kernel.org/all/huduxtn6parzgiaf5cyiyrrvjjvx6jsdedowvrd4nkwmuyeind@j6migjgofh2i/

Changes since v1:
- Preserve the later hard error from bpf_exec_tx_verdict() after waiting
  for any earlier async encryption queued in the same verdict drain loop.
- Flush completed async records after that local wait.
- Check bpf_program__fd() before bpf_prog_attach() in the selftest.
- Leave the __SK_REDIRECT socket-lock-drop finding out of this series;
  it appears pre-existing and should be handled separately if maintainers
  want to pursue it.

Christopher Lusk (2):
  net: tls: preserve split open record on async encrypt
  selftests: net: add kTLS async split record regression

 net/tls/tls_sw.c                              |  40 +-
 tools/testing/selftests/net/Makefile          |   5 +
 .../selftests/net/ktls_async_split.bpf.c      |  24 ++
 .../testing/selftests/net/ktls_async_split.c  | 393 ++++++++++++++++++
 4 files changed, 454 insertions(+), 8 deletions(-)
 create mode 100644 tools/testing/selftests/net/ktls_async_split.bpf.c
 create mode 100644 tools/testing/selftests/net/ktls_async_split.c

-- 
2.54.0