Add a new selftest to verify netconsole's handling of messages that exceed the packet size limit and require fragmentation. The test sends messages with varying sizes and userdata, validating that:

1. Large messages are correctly fragmented and reassembled 2. Userdata fields are properly preserved across fragments 3. Messages work correctly with and without kernel release version appending

The test creates a networking environment using netdevsim, sends messages through /dev/kmsg, and verifies the received fragments maintain message integrity.

Signed-off-by: Breno Leitao leitao@debian.org Reviewed-by: Simon Horman horms@kernel.org --- Changes compared to RFC - Removed the long-line comment (Simon) - Added Simon's reviwed-by tag. - Link to v1: https://lore.kernel.org/r/20250131-netcons_frag_msgs-v1-1-0de83bf2a7e6@debia... --- tools/testing/selftests/drivers/net/Makefile | 1 + .../selftests/drivers/net/lib/sh/lib_netcons.sh | 7 ++ .../drivers/net/netcons_fragmented_msg.sh | 122 +++++++++++++++++++++ 3 files changed, 130 insertions(+)

diff --git a/tools/testing/selftests/drivers/net/Makefile b/tools/testing/selftests/drivers/net/Makefile index 137470bdee0c7fd2517bd1baafc12d575de4b4ac..c7f1c443f2af091aa13f67dd1df9ae05d7a43f40 100644 --- a/tools/testing/selftests/drivers/net/Makefile +++ b/tools/testing/selftests/drivers/net/Makefile @@ -7,6 +7,7 @@ TEST_INCLUDES := $(wildcard lib/py/*.py) \

TEST_PROGS := \ netcons_basic.sh \ + netcons_fragmented_msg.sh \ netcons_overflow.sh \ ping.py \ queues.py \ diff --git a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh index 3acaba41ac7b21aa2fd8457ed640a5ac8a41bc12..0c262b123fdd3082c40b2bd899ec626d223226ed 100644 --- a/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh +++ b/tools/testing/selftests/drivers/net/lib/sh/lib_netcons.sh @@ -110,6 +110,13 @@ function create_dynamic_target() { echo 1 > "${NETCONS_PATH}"/enabled }

+# Do not append the release to the header of the message +function disable_release_append() { + echo 0 > "${NETCONS_PATH}"/enabled + echo 0 > "${NETCONS_PATH}"/release + echo 1 > "${NETCONS_PATH}"/enabled +} + function cleanup() { local NSIM_DEV_SYS_DEL="/sys/bus/netdevsim/del_device"

diff --git a/tools/testing/selftests/drivers/net/netcons_fragmented_msg.sh b/tools/testing/selftests/drivers/net/netcons_fragmented_msg.sh new file mode 100755 index 0000000000000000000000000000000000000000..4a71e01a230c75c14147a9937920fe0b68a0926a --- /dev/null +++ b/tools/testing/selftests/drivers/net/netcons_fragmented_msg.sh @@ -0,0 +1,122 @@ +#!/usr/bin/env bash +# SPDX-License-Identifier: GPL-2.0 + +# Test netconsole's message fragmentation functionality. +# +# When a message exceeds the maximum packet size, netconsole splits it into +# multiple fragments for transmission. This test verifies: +# - Correct fragmentation of large messages +# - Proper reassembly of fragments at the receiver +# - Preservation of userdata across fragments +# - Behavior with and without kernel release version appending +# +# Author: Breno Leitao leitao@debian.org + +set -euo pipefail + +SCRIPTDIR=$(dirname "$(readlink -e "${BASH_SOURCE[0]}")") + +source "${SCRIPTDIR}"/lib/sh/lib_netcons.sh + +modprobe netdevsim 2> /dev/null || true +modprobe netconsole 2> /dev/null || true + +# The content of kmsg will be save to the following file +OUTPUT_FILE="/tmp/${TARGET}" + +# set userdata to a long value. In this case, it is "1-2-3-4...50-" +USERDATA_VALUE=$(printf -- '%.2s-' {1..60}) + +# Convert the header string in a regexp, so, we can remove +# the second header as well. +# A header looks like "13,468,514729715,-,ncfrag=0/1135;". If +# release is appended, you might find something like:L +# "6.13.0-04048-g4f561a87745a,13,468,514729715,-,ncfrag=0/1135;" +function header_to_regex() { + # header is everything before ; + local HEADER="${1}" + REGEX=$(echo "${HEADER}" | cut -d'=' -f1) + echo "${REGEX}=[0-9]*/[0-9]*;" +} + +# We have two headers in the message. Remove both to get the full message, +# and extract the full message. +function extract_msg() { + local MSGFILE="${1}" + # Extract the header, which is the very first thing that arrives in the + # first list. + HEADER=$(sed -n '1p' "${MSGFILE}" | cut -d';' -f1) + HEADER_REGEX=$(header_to_regex "${HEADER}") + + # Remove the two headers from the received message + # This will return the message without any header, similarly to what + # was sent. + sed "s/""${HEADER_REGEX}""//g" "${MSGFILE}" +} + +# Validate the message, which has two messages glued together. +# unwrap them to make sure all the characters were transmitted. +# File will look like the following: +# 13,468,514729715,-,ncfrag=0/1135;<message> +# key=<part of key>-13,468,514729715,-,ncfrag=967/1135;<rest of the key> +function validate_fragmented_result() { + # Discard the netconsole headers, and assemble the full message + RCVMSG=$(extract_msg "${1}") + + # check for the main message + if ! echo "${RCVMSG}" | grep -q "${MSG}"; then + echo "Message body doesn't match." >&2 + echo "msg received=" "${RCVMSG}" >&2 + exit "${ksft_fail}" + fi + + # check userdata + if ! echo "${RCVMSG}" | grep -q "${USERDATA_VALUE}"; then + echo "message userdata doesn't match" >&2 + echo "msg received=" "${RCVMSG}" >&2 + exit "${ksft_fail}" + fi + # test passed. hooray +} + +# Check for basic system dependency and exit if not found +check_for_dependencies +# Set current loglevel to KERN_INFO(6), and default to KERN_NOTICE(5) +echo "6 5" > /proc/sys/kernel/printk +# Remove the namespace, interfaces and netconsole target on exit +trap cleanup EXIT +# Create one namespace and two interfaces +set_network +# Create a dynamic target for netconsole +create_dynamic_target +# Set userdata "key" with the "value" value +set_user_data + + +# TEST 1: Send message and userdata. They will fragment +# ======= +MSG=$(printf -- 'MSG%.3s=' {1..150}) + +# Listen for netconsole port inside the namespace and destination interface +listen_port_and_save_to "${OUTPUT_FILE}" & +# Wait for socat to start and listen to the port. +wait_local_port_listen "${NAMESPACE}" "${PORT}" udp +# Send the message +echo "${MSG}: ${TARGET}" > /dev/kmsg +# Wait until socat saves the file to disk +busywait "${BUSYWAIT_TIMEOUT}" test -s "${OUTPUT_FILE}" +# Check if the message was not corrupted +validate_fragmented_result "${OUTPUT_FILE}" + +# TEST 2: Test with smaller message, and without release appended +# ======= +MSG=$(printf -- 'FOOBAR%.3s=' {1..100}) +# Let's disable release and test again. +disable_release_append + +listen_port_and_save_to "${OUTPUT_FILE}" & +wait_local_port_listen "${NAMESPACE}" "${PORT}" udp +echo "${MSG}: ${TARGET}" > /dev/kmsg +busywait "${BUSYWAIT_TIMEOUT}" test -s "${OUTPUT_FILE}" +validate_fragmented_result "${OUTPUT_FILE}" +exit "${ksft_pass}"

--- base-commit: 0ad9617c78acbc71373fb341a6f75d4012b01d69 change-id: 20250129-netcons_frag_msgs-91506d136f50

Best regards,