Subject: Re: [PATCH net-next RFC] selftests/net: integrate packetdrill with ksft

From: Stanislav Fomichev <[email-masked]>
Date: Wed, 28 Aug 2024 10:20:47 -0700

On 08/28, Willem de Bruijn wrote:
> Stanislav Fomichev wrote:
> > On 08/27, Willem de Bruijn wrote:
> > > From: Willem de Bruijn <[email-masked]>
> > > 
> > > Lay the groundwork to import into kselftests the over 150 packetdrill
> > > TCP/IP conformance tests on github.com/google/packetdrill.
> > > 
> > > Florian recently added support for packetdrill tests in nf_conntrack,
> > > in commit a8a388c2aae49 ("selftests: netfilter: add packetdrill based
> > > conntrack tests").
> > > 
> > > This patch takes a slightly different implementation and reuses the
> > > ksft python library for its KTAP, ksft, NetNS and other such tooling.
> > > 
> > > It also anticipates the large number of testcases, by creating a
> > > separate kselftest for each feature (directory). It does this by
> > > copying the template script packetdrill_ksft.py for each directory,
> > > and putting those in TEST_CUSTOM_PROGS so that kselftests runs each.
> > > 
> > > To demonstrate the code with minimal patch size, initially import only
> > > two features/directories from github. One with a single script, and
> > > one with two. This was the only reason to pick tcp/inq and tcp/md5.
> > > 
> > > Any future imports of packetdrill tests should require no additional
> > > coding. Just add the tcp/$FEATURE directory with *.pkt files.
> > > 
> > > Implementation notes:
> > > - restore alphabetical order when adding the new directory to
> > >   tools/testing/selftests/Makefile
> > > - copied *.pkt files and support verbatim from the github project,
> > >   except for
> > >     - update common/defaults.sh path (there are two paths on github)
> > >     - add SPDX headers
> > >     - remove one author statement
> > >     - Acknowledgment: drop an e (checkpatch)
> > > 
> > > Tested:
> > > 	make -C tools/testing/selftests/ \
> > > 	  TARGETS=net/packetdrill \
> > > 	  install INSTALL_PATH=$KSFT_INSTALL_PATH
> > > 
> > > 	# in virtme-ng
> > > 	sudo ./run_kselftest.sh -c net/packetdrill
> > > 	sudo ./run_kselftest.sh -t net/packetdrill:tcp_inq.py
> > > 
> > > Result:
> > > 	kselftest: Running tests in net/packetdrill
> > > 	TAP version 13
> > > 	1..2
> > > 	# timeout set to 45
> > > 	# selftests: net/packetdrill: tcp_inq.py
> > > 	# KTAP version 1
> > > 	# 1..4
> > > 	# ok 1 tcp_inq.client-v4
> > > 	# ok 2 tcp_inq.client-v6
> > > 	# ok 3 tcp_inq.server-v4
> > > 	# ok 4 tcp_inq.server-v6
> > > 	# # Totals: pass:4 fail:0 xfail:0 xpass:0 skip:0 error:0
> > > 	ok 1 selftests: net/packetdrill: tcp_inq.py
> > > 	# timeout set to 45
> > > 	# selftests: net/packetdrill: tcp_md5.py
> > > 	# KTAP version 1
> > > 	# 1..2
> > > 	# ok 1 tcp_md5.md5-only-on-client-ack-v4
> > > 	# ok 2 tcp_md5.md5-only-on-client-ack-v6
> > > 	# # Totals: pass:2 fail:0 xfail:0 xpass:0 skip:0 error:0
> > > 	ok 2 selftests: net/packetdrill: tcp_md5.py
> > > 
> > > Signed-off-by: Willem de Bruijn <[email-masked]>
> > > 
> > > ---
> > > 
> > > RFC points for discussion
> > > 
> > > ksft: the choice for this python framework introduces a dependency on
> > > the YNL scripts, and some non-obvious code:
> > > - to include the net/lib dep in tools/testing/selftests/Makefile
> > > - a boilerplate lib/py/__init__.py that each user of ksft will need
> > > It seems preferable to me to use ksft.py over reinventing the wheel,
> > > e.g., to print KTAP output. But perhaps we can make it more obvious
> > > for future ksft users, and make the dependency on YNL optional.
> > > 
> > > kselftest-per-directory: copying packetdrill_ksft.py to create a
> > > separate script per dir is a bit of a hack. A single script is much
> > > simpler, optionally with nested KTAP (not supported yet by ksft). But,
> > > I'm afraid that running time without intermediate output will be very
> > > long when we integrate all packetdrill scripts.
> > > 
> > > nf_conntrack: we can dedup the common.sh.
> > > 
> > > *pkt files: which of the 150+ scripts on github are candidates for
> > > kselftests, all or a subset? To avoid change detector tests. And what
> > > is the best way to eventually send up to 150 files, 7K LoC.
> > > ---
> > >  tools/testing/selftests/Makefile              |  7 +-
> > >  .../selftests/net/packetdrill/.gitignore      |  1 +
> > >  .../selftests/net/packetdrill/Makefile        | 28 ++++++
> > >  .../net/packetdrill/lib/py/__init__.py        | 15 ++++
> > >  .../net/packetdrill/packetdrill_ksft.py       | 90 +++++++++++++++++++
> > >  .../net/packetdrill/tcp/common/defaults.sh    | 63 +++++++++++++
> > >  .../net/packetdrill/tcp/common/set_sysctls.py | 38 ++++++++
> > >  .../net/packetdrill/tcp/inq/client.pkt        | 51 +++++++++++
> > >  .../net/packetdrill/tcp/inq/server.pkt        | 51 +++++++++++
> > >  .../tcp/md5/md5-only-on-client-ack.pkt        | 28 ++++++
> > >  10 files changed, 369 insertions(+), 3 deletions(-)
> > >  create mode 100644 tools/testing/selftests/net/packetdrill/.gitignore
> > >  create mode 100644 tools/testing/selftests/net/packetdrill/Makefile
> > >  create mode 100644 tools/testing/selftests/net/packetdrill/lib/py/__init__.py
> > >  create mode 100755 tools/testing/selftests/net/packetdrill/packetdrill_ksft.py
> > >  create mode 100755 tools/testing/selftests/net/packetdrill/tcp/common/defaults.sh
> > >  create mode 100755 tools/testing/selftests/net/packetdrill/tcp/common/set_sysctls.py
> > >  create mode 100644 tools/testing/selftests/net/packetdrill/tcp/inq/client.pkt
> > >  create mode 100644 tools/testing/selftests/net/packetdrill/tcp/inq/server.pkt
> > >  create mode 100644 tools/testing/selftests/net/packetdrill/tcp/md5/md5-only-on-client-ack.pkt
> > > 
> > > diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
> > > index a5f1c0c27dff9..f03d6fee7ac54 100644
> > > --- a/tools/testing/selftests/Makefile
> > > +++ b/tools/testing/selftests/Makefile
> > > @@ -65,10 +65,11 @@ TARGETS += net/af_unix
> > >  TARGETS += net/forwarding
> > >  TARGETS += net/hsr
> > >  TARGETS += net/mptcp
> > > -TARGETS += net/openvswitch
> > > -TARGETS += net/tcp_ao
> > >  TARGETS += net/netfilter
> > > +TARGETS += net/openvswitch
> > > +TARGETS += net/packetdrill
> > >  TARGETS += net/rds
> > > +TARGETS += net/tcp_ao
> > >  TARGETS += nsfs
> > >  TARGETS += perf_events
> > >  TARGETS += pidfd
> > > @@ -122,7 +123,7 @@ TARGETS_HOTPLUG = cpu-hotplug
> > >  TARGETS_HOTPLUG += memory-hotplug
> > >  
> > >  # Networking tests want the net/lib target, include it automatically
> > > -ifneq ($(filter net drivers/net drivers/net/hw,$(TARGETS)),)
> > > +ifneq ($(filter net net/packetdrill drivers/net drivers/net/hw,$(TARGETS)),)
> > >  ifeq ($(filter net/lib,$(TARGETS)),)
> > >  	INSTALL_DEP_TARGETS := net/lib
> > >  endif
> > > diff --git a/tools/testing/selftests/net/packetdrill/.gitignore b/tools/testing/selftests/net/packetdrill/.gitignore
> > > new file mode 100644
> > > index 0000000000000..a40f1a600eb94
> > > --- /dev/null
> > > +++ b/tools/testing/selftests/net/packetdrill/.gitignore
> > > @@ -0,0 +1 @@
> > > +tcp*sh
> > > diff --git a/tools/testing/selftests/net/packetdrill/Makefile b/tools/testing/selftests/net/packetdrill/Makefile
> > > new file mode 100644
> > > index 0000000000000..d94c51098d1f0
> > > --- /dev/null
> > > +++ b/tools/testing/selftests/net/packetdrill/Makefile
> > > @@ -0,0 +1,28 @@
> > > +# SPDX-License-Identifier: GPL-2.0
> > > +
> > > +# KSFT includes
> > > +TEST_INCLUDES := $(wildcard lib/py/*.py ../lib/py/*.py)
> > > +
> > > +# Packetdrill support file(s)
> > > +TEST_INCLUDES += tcp/common/defaults.sh
> > > +TEST_INCLUDES += tcp/common/set_sysctls.py
> > > +
> > > +# Packetdrill scripts: all .pkt in subdirectories
> > > +TEST_INCLUDES += $(wildcard tcp/**/*.pkt)
> > > +
> > > +# Create a separate ksft test for each subdirectory
> > > +# Running all packetdrill tests in one go will take too long
> > > +#
> > > +# For each tcp/$subdir, create a test script tcp_$subdir.py
> > > +# Exclude tcp/common, which is a helper directory
> > > +TEST_DIRS := $(wildcard tcp/*)
> > > +TEST_DIRS := $(filter-out tcp/common, $(TEST_DIRS))
> > > +TEST_CUSTOM_PROGS := $(foreach dir,$(TEST_DIRS),$(subst /,_,$(dir)).py)
> > > +
> > > +$(TEST_CUSTOM_PROGS) : packetdrill_ksft.py
> > > +	cp $< $@
> > > +
> > > +# Needed to generate all TEST_CUSTOM_PROGS
> > > +all: $(TEST_CUSTOM_PROGS)
> > > +
> > > +include ../../lib.mk
> > > diff --git a/tools/testing/selftests/net/packetdrill/lib/py/__init__.py b/tools/testing/selftests/net/packetdrill/lib/py/__init__.py
> > > new file mode 100644
> > > index 0000000000000..51bb6dda43d65
> > > --- /dev/null
> > > +++ b/tools/testing/selftests/net/packetdrill/lib/py/__init__.py
> > > @@ -0,0 +1,15 @@
> > > +# SPDX-License-Identifier: GPL-2.0
> > > +
> > > +import pathlib
> > > +import sys
> > > +
> > > +KSFT_DIR = (pathlib.Path(__file__).parent / "../../../..").resolve()
> > > +
> > > +try:
> > > +    sys.path.append(KSFT_DIR.as_posix())
> > > +    from net.lib.py import *
> > > +except ModuleNotFoundError as e:
> > > +    ksft_pr("Failed importing `net` library from kernel sources")
> > > +    ksft_pr(str(e))
> > > +    ktap_result(True, comment="SKIP")
> > > +    sys.exit(4)
> > > diff --git a/tools/testing/selftests/net/packetdrill/packetdrill_ksft.py b/tools/testing/selftests/net/packetdrill/packetdrill_ksft.py
> > > new file mode 100755
> > > index 0000000000000..62572a5b8331c
> > > --- /dev/null
> > > +++ b/tools/testing/selftests/net/packetdrill/packetdrill_ksft.py
> > > @@ -0,0 +1,90 @@
> > > +#!/usr/bin/env python3
> > > +# SPDX-License-Identifier: GPL-2.0
> > > +
> > > +"""Run packetdrill tests in the ksft harness.
> > > +
> > > +   Run all packetdrill tests in a subdirectory.
> > > +   Detect the relevant subdirectory from this script name.
> > > +   (Because the script cannot be given arguments.)
> > > +
> > > +   Run each test, for both IPv4 and IPv6.
> > > +   Return a separate ksft result for each test case.
> > > +"""
> > > +
> > > +import glob
> > > +import os
> > > +import pathlib
> > > +import shutil
> > > +
> > > +from lib.py import cmd, ksft_exit, ksft_run, KsftSkipEx, NetNS
> > > +
> > > +
> > > +def test_func_builder(pktfile_path, ipv4):
> > > +    """Create a function that can be passed to ksft_run."""
> > > +
> > > +    def f():
> > > +        if ipv4:
> > > +            args = ("--ip_version=ipv4 "
> > > +                    "--local_ip=192.168.0.1 "
> > > +                    "--gateway_ip=192.168.0.1 "
> > > +                    "--netmask_ip=255.255.0.0 "
> > > +                    "--remote_ip=192.0.2.1 "
> > > +                    "-D CMSG_LEVEL_IP=SOL_IP "
> > > +                    "-D CMSG_TYPE_RECVERR=IP_RECVERR "
> > > +                    )
> > > +        else:
> > > +            args = ("--ip_version=ipv6 --mtu=1520 "
> > > +                    "--local_ip=fd3d:0a0b:17d6::1 "
> > > +                    "--gateway_ip=fd3d:0a0b:17d6:8888::1 "
> > > +                    "--remote_ip=fd3d:fa7b:d17d::1 "
> > > +                    "-D CMSG_LEVEL_IP=SOL_IPV6 "
> > > +                    "-D CMSG_TYPE_RECVERR=IPV6_RECVERR"
> > > +                    )
> > > +
> > > +        if not shutil.which("packetdrill"):
> > > +            raise KsftSkipEx("Cannot find packetdrill")
> > 
> > I don't see anything about building the binary itself. Am I missing
> > something or should we also have some makefile magic to do it?
> > I'm not sure packetdrill is packaged by the distros... Presumably
> > we want the existing NIPA runners to run those tests as well?
> 
> As Jakub responded.
> 
> Indeed importing the whole application into the kernel sources is what
> stopped me from attempting this before. Florian's nf_conntrack charted
> the path here.

Thanks both. I was expecting to find some build rules :-) But as long
as we have this story sorted out, we're good.
 
> > > +
> > > +        netns = NetNS()
> > > +
> > > +        # Call packetdrill from the directory hosting the .pkt script,
> > > +        # because scripts can have relative includes.
> > > +        savedir = os.getcwd()
> > > +        os.chdir(os.path.dirname(pktfile_path))
> > > +        basename = os.path.basename(pktfile_path)
> > > +        cmd(f"packetdrill {args} {basename}", ns=netns)
> > > +        os.chdir(savedir)
> > > +
> > > +    if ipv4:
> > > +        f.__name__ = pathlib.Path(pktfile_path).stem + "-v4"
> > > +    else:
> > > +        f.__name__ = pathlib.Path(pktfile_path).stem + "-v6"
> > 
> > What about dualstack v4-over-v6 mode? Do we want to support that as
> > well?
> 
> Does it give a sufficient signal? I skipped over it on purpose. But
> can enable if that is the consensus.

Makes sense. Agreed that most of the time v4-over-v6 just exercises
the same v4 paths so it's not too much value. I'm assuming that the tests
that care about v4-over-v6 peculiarities can just
do --ip_version=ipv4-mapped-ipv6 in their .pkt file (similar to
what gtests/net/tcp/mtu_probe/basic-v6.pkt is doing)?