From: Willem de Bruijn <willemb@google.com>

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 <willemb@google.com>

---

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")