[PATCH net-next v4 0/8] net/selftests: TCP-AO selftests updates

Dmitry Safonov via B4 Relay
2024-08-23T22:05:18Z

First 3 patches are more-or-less cleanups/preparations.

Patches 4/5 are fixes for netns file descriptors leaks/open.

Patch 6 was sent to me/contributed off-list by Mohammad, who wants 32-bit
kernels to run TCP-AO.

Patch 7 is a workaround/fix for slow VMs. Albeit, I can't reproduce
the issue, but I hope it will fix netdev flakes for connect-deny-*
tests.

And the biggest change is adding TCP-AO tracepoints to selftests.
I think it's a good addition by the following reasons:
- The related tracepoints are now tested;
- It allows tcp-ao selftests to raise expectations on the kernel
behavior - up from the syscalls exit statuses + net counters.
- Provides tracepoints usage samples.

As tracepoints are not a stable ABI, any kernel changes done to them
will be reflected to the selftests, which also will allow users
to see how to change their code. It's quite better than parsing dmesg
(what BGP was doing pre-tracepoints, ugh).

Somewhat arguably, the code parses trace_pipe, rather than uses
libtraceevent (which any sane user should do). The reason behind that is
the same as for rt-netlink macros instead of libmnl: I'm trying
to minimize the library dependencies of the selftests. And the
performance of formatting text in kernel and parsing it again in a test
is not critical.

Current output sample:
> ok 73 Trace events matched expectations: 13 tcp_hash_md5_required[2] tcp_hash_md5_unexpected[4] tcp_hash_ao_required[3] tcp_ao_key_not_found[4]

Previously, tracepoints selftests were part of kernel tcp tracepoints
submission [1], but since then the code was quite changed:
- Now generic tracing setup is in lib/ftrace.c, separate from
lib/ftrace-tcp.c which utilizes TCP trace points. This separation
allows future selftests to trace non-TCP events, i.e. to find out
an skb's drop reason, which was useful in the creation of TCP-CLOSE
stress-test (not in this patch set, but used in attempt to reproduce
the issue from [2]).
- Another change is that in the previous submission the trace events
where used only to detect unexpected TCP-AO/TCP-MD5 events. In this
version the selftests will fail if an expected trace event didn't
appear.
Let's see how reliable this is on the netdev bot - it obviously passes
on my testing, but potentially may require a temporary XFAIL patch
if it misbehaves on a slow VM.

[1] https://lore.kernel.org/lkml/20240224-tcp-ao-tracepoints-v1-0-15f31b7f30a7@arista.com/
[2] https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=33700a0c9b56

Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com>
---
In v4 mostly worked on non-appearing events on netdev test VM.
- Set up x86 VM with the config from netdev & run stress-ng didn't
reproduce the isssue.
- Spread more error messages if tracing pthread fails to start
- Added conditional wait for tracer thread, just before destruction, in
case it didn't had a time slice to run and parse trace events.
- Addressed some of checkpatch.pl --strict warnings (with
nits from Simon Horman)
- Link to v3: https://lore.kernel.org/r/20240815-tcp-ao-selftests-upd-6-12-v3-0-7bd2e22bb81c@gmail.com

Changes in v3:
- Corrected the selftests printing of tcp header flags, parsed from
trace points
- Fixed an issue with VRF kconfig checks (and tests)
- Made check for unexpected trace events XFAIL, yet looking into the
reason behind the fail
- Link to v2: https://lore.kernel.org/r/20240802-tcp-ao-selftests-upd-6-12-v2-0-370c99358161@gmail.com

Changes in v2:
- Fixed two issues with parsing TCP-AO events: the socket state and TCP
segment flags. Hopefully, won't fail on netdev.
- Reword patch 1 & 2 messages to be more informative and at some degree
formal (Paolo)
- Since commit e33a02ed6a4f ("selftests: Add printf attribute to
kselftest prints") it's possible to use __printf instead of "raw" gcc
attribute - switch using that, as checkpatch suggests.
- Link to v1: https://lore.kernel.org/r/20240730-tcp-ao-selftests-upd-6-12-v1-0-ffd4bf15d638@gmail.com

---
Dmitry Safonov (7):
selftests/net: Clean-up double assignment
selftests/net: Provide test_snprintf() helper
selftests/net: Be consistent in kconfig checks
selftests/net: Open /proc/thread-self in open_netns()
selftests/net: Don't forget to close nsfd after switch_save_ns()
selftests/net: Synchronize client/server before counters checks
selftests/net: Add trace events matching to tcp_ao

Mohammad Nassiri (1):
selftests/tcp_ao: Fix printing format for uint64_t

tools/testing/selftests/net/tcp_ao/Makefile | 3 +-
tools/testing/selftests/net/tcp_ao/bench-lookups.c | 2 +-
tools/testing/selftests/net/tcp_ao/config | 1 +
tools/testing/selftests/net/tcp_ao/connect-deny.c | 25 +-
tools/testing/selftests/net/tcp_ao/connect.c | 6 +-
tools/testing/selftests/net/tcp_ao/icmps-discard.c | 2 +-
.../testing/selftests/net/tcp_ao/key-management.c | 18 +-
tools/testing/selftests/net/tcp_ao/lib/aolib.h | 178 ++++++-
.../testing/selftests/net/tcp_ao/lib/ftrace-tcp.c | 559 +++++++++++++++++++++
tools/testing/selftests/net/tcp_ao/lib/ftrace.c | 543 ++++++++++++++++++++
tools/testing/selftests/net/tcp_ao/lib/kconfig.c | 31 +-
tools/testing/selftests/net/tcp_ao/lib/setup.c | 17 +-
tools/testing/selftests/net/tcp_ao/lib/sock.c | 1 -
tools/testing/selftests/net/tcp_ao/lib/utils.c | 26 +
tools/testing/selftests/net/tcp_ao/restore.c | 30 +-
tools/testing/selftests/net/tcp_ao/rst.c | 2 +-
tools/testing/selftests/net/tcp_ao/self-connect.c | 19 +-
tools/testing/selftests/net/tcp_ao/seq-ext.c | 28 +-
.../selftests/net/tcp_ao/setsockopt-closed.c | 6 +-
tools/testing/selftests/net/tcp_ao/unsigned-md5.c | 35 +-
20 files changed, 1465 insertions(+), 67 deletions(-)
---
base-commit: f9db28bb09f46087580f2a8da54bb0aab59a8024
change-id: 20240730-tcp-ao-selftests-upd-6-12-4d3e53a74f3f

Best regards,
--
Dmitry Safonov <0x7f454c46@gmail.com>