Adds a selftest that creates two virtual interfaces, assigns one to a
new namespace, and assigns IP addresses to both.

It listens on the destination interface using netcat and configures a
dynamic target on netconsole, pointing to the destination IP address.

The test then checks if the message was received properly on the
destination interface.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
 MAINTAINERS                                   |   1 +
 .../net/netconsole/basic_integration_test.sh  | 153 ++++++++++++++++++
 2 files changed, 154 insertions(+)
 create mode 100755 tools/testing/selftests/net/netconsole/basic_integration_test.sh

diff --git a/MAINTAINERS b/MAINTAINERS
index c0a3d9e93689..59207365c9f5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15768,6 +15768,7 @@ M:	Breno Leitao <leitao@debian.org>
 S:	Maintained
 F:	Documentation/networking/netconsole.rst
 F:	drivers/net/netconsole.c
+F:	tools/testing/selftests/net/netconsole/
 
 NETDEVSIM
 M:	Jakub Kicinski <kuba@kernel.org>
diff --git a/tools/testing/selftests/net/netconsole/basic_integration_test.sh b/tools/testing/selftests/net/netconsole/basic_integration_test.sh
new file mode 100755
index 000000000000..fbabbc633451
--- /dev/null
+++ b/tools/testing/selftests/net/netconsole/basic_integration_test.sh
@@ -0,0 +1,153 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: GPL-2.0
+
+# This test creates two virtual interfaces, assigns one of them (the "destination
+# interface") to a new namespace, and assigns IP addresses to both interfaces.
+#
+# It listens on the destination interface using netcat (nc) and configures a
+# dynamic target on netconsole, pointing to the destination IP address.
+#
+# Finally, it checks whether the message was received properly on the
+# destination interface.  Note that this test may pollute the kernel log buffer
+# (dmesg) and relies on dynamic configuration and namespaces being configured."
+#
+# Author: Breno Leitao <leitao@debian.org>
+
+SCRIPTDIR=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")")
+
+# Simple script to test dynamic targets in netconsole
+SRCIF="veth0"
+SRCIP=192.168.1.1
+
+DSTIF="veth1"
+DSTIP=192.168.1.2
+
+PORT="6666"
+MSG="netconsole selftest"
+TARGET=$(mktemp -u netcons_XXXXX)
+NETCONS_CONFIGFS="/sys/kernel/config/netconsole"
+FULLPATH="${NETCONS_CONFIGFS}"/"${TARGET}"
+# This will be have some tmp values appened to it in set_network()
+NAMESPACE="netconsns"
+
+# Used to create and delete namespaces
+source "${SCRIPTDIR}"/../lib.sh
+
+function set_network() {
+	# this is coming from lib.sh
+	setup_ns "${NAMESPACE}"
+	NAMESPACE=${NS_LIST[0]}
+	ip link add "${SRCIF}" type veth peer name "${DSTIF}"
+
+	# "${DSTIF}"
+	ip link set "${DSTIF}" netns "${NAMESPACE}"
+	ip netns exec "${NAMESPACE}" ip addr add "${DSTIP}"/24 dev "${DSTIF}"
+	ip netns exec "${NAMESPACE}" ip link set "${DSTIF}" up
+
+	# later, configure "${SRCIF}"
+	ip addr add "${SRCIP}"/24 dev "${SRCIF}"
+	ip link set "${SRCIF}" up
+}
+
+function create_dynamic_target() {
+	DSTMAC=$(ip netns exec "${NAMESPACE}" ip link show "${DSTIF}" | awk '/ether/ {print $2}')
+
+	# Create a dynamic target
+	mkdir ${FULLPATH}
+
+	echo ${DSTIP} > ${FULLPATH}/remote_ip
+	echo ${SRCIP} > ${FULLPATH}/local_ip
+	echo ${DSTMAC} > ${FULLPATH}/remote_mac
+	echo "${SRCIF}" > ${FULLPATH}/dev_name
+
+	echo 1 > ${FULLPATH}/enabled
+}
+
+function cleanup() {
+	echo 0 > "${FULLPATH}"/enabled
+	rmdir "${FULLPATH}"
+	# This will delete DSTIF also
+	ip link del "${SRCIF}"
+	# this is coming from lib.sh
+	cleanup_all_ns
+}
+
+function listen_port() {
+	OUTPUT=${1}
+	echo "Saving content in ${OUTPUT}"
+	timeout 2 ip netns exec "${NAMESPACE}" nc -u -l "${PORT}" | sed '/^$/q' > ${OUTPUT}
+}
+
+function validate_result() {
+	TMPFILENAME=/tmp/"${TARGET}"
+
+	# sleep until the file isc reated
+	sleep 1
+	# Check if the file exists
+	if [ ! -f "$TMPFILENAME" ]; then
+	    echo "FAIL: File was not generate." >&2
+	    return ${ksft_fail}
+	fi
+
+	if ! grep -q "${MSG}" "${TMPFILENAME}"; then
+	    echo "FAIL: ${MSG} not found in ${TMPFILENAME}" >&2
+	    cat ${TMPFILENAME} >&2
+	    return ${ksft_fail}
+	fi
+
+	rm ${TMPFILENAME}
+	return ${ksft_pass}
+}
+
+function check_for_dependencies() {
+	if [ "$(id -u)" -ne 0 ]; then
+		echo "This script must be run as root" >&2
+		exit 1
+	fi
+
+	if ! which nc > /dev/null ; then
+		echo "SKIP: nc(1) is not available" >&2
+		exit ${ksft_skip}
+	fi
+
+	if ! which ip > /dev/null ; then
+		echo "SKIP: ip(1) is not available" >&2
+		exit ${ksft_skip}
+	fi
+
+	if [ ! -d "${NETCONS_CONFIGFS}" ]; then
+		echo "SKIP: directory ${NETCONS_CONFIGFS} does not exist. Check if NETCONSOLE_DYNAMIC is enabled" >&2
+		exit ${ksft_skip}
+	fi
+
+	if ip link show veth0 2> /dev/null; then
+		echo "SKIP: interface veth0 exists in the system. Not overwriting it."
+		exit ${ksft_skip}
+	fi
+}
+
+# ========== #
+# Start here #
+# ========== #
+
+# Check for basic system dependency and exit if not found
+check_for_dependencies
+# Create one namespace and two interfaces
+set_network
+# Create a dynamic target for netconsole
+create_dynamic_target
+# Listed for netconsole port inside the namespace and destination interface
+listen_port /tmp/"${TARGET}" &
+# Wait for nc to start and listen to the port.
+sleep 1
+
+# Send the message
+echo "${MSG}: ${TARGET}" > /dev/kmsg
+
+# Make sure the message was received in the dst part
+validate_result
+ret=$?
+# Remove the namespace, interfaces and netconsole target
+cleanup
+
+exit ${ret}
-- 
2.43.0

On Thu,  1 Aug 2024 09:11:58 -0700 Breno Leitao wrote:
>  .../net/netconsole/basic_integration_test.sh  | 153 ++++++++++++++++++

It needs to be included in a Makefile
If we only have one script I'd put it directly in .../net/, 
or drivers/netdevsim/? each target should technically have
a Kconfig, Makefile, settings, no point for a single script.

Hello Jakub,

On Thu, Aug 01, 2024 at 09:53:22AM -0700, Jakub Kicinski wrote:
> On Thu,  1 Aug 2024 09:11:58 -0700 Breno Leitao wrote:
> >  .../net/netconsole/basic_integration_test.sh  | 153 ++++++++++++++++++
> 
> It needs to be included in a Makefile
> If we only have one script I'd put it directly in .../net/, 
> or drivers/netdevsim/? each target should technically have
> a Kconfig, Makefile, settings, no point for a single script.

Thanks for the feedback, I will wait a bit for more feedback, and then
send a v2 where I would move the script back to .../net.

--breno