[PATCH net-next v15 09/12] selftests/vsock: add tests for proc sys vsock ns_mode

Bobby Eshleman
2026-01-16T21:29:12Z

Add tests for the /proc/sys/net/vsock/{ns_mode,child_ns_mode}
interfaces. Namely, that they accept/report "global" and "local" strings
and enforce their access policies.

Start a convention of commenting the test name over the test
description. Add test name comments over test descriptions that existed
before this convention.

Add a check_netns() function that checks if the test requires namespaces
and if the current kernel supports namespaces. Skip tests that require
namespaces if the system does not have namespace support.

This patch is the first to add tests that do *not* re-use the same
shared VM. For that reason, it adds a run_ns_tests() function to run
these tests and filter out the shared VM tests.

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
---
Changes in v13:
- remove write-once test ns_host_vsock_ns_mode_write_once_ok to reflect
removing the write-once policy
- add child_ns_mode test test_ns_host_vsock_child_ns_mode_ok
- modify test_ns_host_vsock_ns_mode_ok() to check that the correct mode
was inherited from child_ns_mode

Changes in v12:
- remove ns_vm_local_mode_rejected test, due to dropping that constraint

Changes in v11:
- Document ns_ prefix above TEST_NAMES (Stefano)

Changes in v10:
- Remove extraneous add_namespaces/del_namespaces calls.
- Rename run_tests() to run_ns_tests() since it is designed to only
run ns tests.

Changes in v9:
- add test ns_vm_local_mode_rejected to check that guests cannot use
local mode
---
tools/testing/selftests/vsock/vmtest.sh | 140 +++++++++++++++++++++++++++++++-
1 file changed, 138 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/vsock/vmtest.sh b/tools/testing/selftests/vsock/vmtest.sh
index 0e681d4c3a15..38785a102236 100755
--- a/tools/testing/selftests/vsock/vmtest.sh
+++ b/tools/testing/selftests/vsock/vmtest.sh
@@ -41,14 +41,38 @@ readonly KERNEL_CMDLINE="\
virtme.ssh virtme_ssh_channel=tcp virtme_ssh_user=$USER \
"
readonly LOG=$(mktemp /tmp/vsock_vmtest_XXXX.log)
-readonly TEST_NAMES=(vm_server_host_client vm_client_host_server vm_loopback)
+
+# Namespace tests must use the ns_ prefix. This is checked in check_netns() and
+# is used to determine if a test needs namespace setup before test execution.
+readonly TEST_NAMES=(
+ vm_server_host_client
+ vm_client_host_server
+ vm_loopback
+ ns_host_vsock_ns_mode_ok
+ ns_host_vsock_child_ns_mode_ok
+)
readonly TEST_DESCS=(
+ # vm_server_host_client
"Run vsock_test in server mode on the VM and in client mode on the host."
+
+ # vm_client_host_server
"Run vsock_test in client mode on the VM and in server mode on the host."
+
+ # vm_loopback
"Run vsock_test using the loopback transport in the VM."
+
+ # ns_host_vsock_ns_mode_ok
+ "Check /proc/sys/net/vsock/ns_mode strings on the host."
+
+ # ns_host_vsock_child_ns_mode_ok
+ "Check /proc/sys/net/vsock/ns_mode is read-only and child_ns_mode is writable."
)

-readonly USE_SHARED_VM=(vm_server_host_client vm_client_host_server vm_loopback)
+readonly USE_SHARED_VM=(
+ vm_server_host_client
+ vm_client_host_server
+ vm_loopback
+)
readonly NS_MODES=("local" "global")

VERBOSE=0
@@ -196,6 +220,20 @@ check_deps() {
fi
}

+check_netns() {
+ local tname=$1
+
+ # If the test requires NS support, check if NS support exists
+ # using /proc/self/ns
+ if [[ "${tname}" =~ ^ns_ ]] &&
+ [[ ! -e /proc/self/ns ]]; then
+ log_host "No NS support detected for test ${tname}"
+ return 1
+ fi
+
+ return 0
+}
+
check_vng() {
local tested_versions
local version
@@ -519,6 +557,54 @@ log_guest() {
LOG_PREFIX=guest log "$@"
}

+ns_get_mode() {
+ local ns=$1
+
+ ip netns exec "${ns}" cat /proc/sys/net/vsock/ns_mode 2>/dev/null
+}
+
+test_ns_host_vsock_ns_mode_ok() {
+ for mode in "${NS_MODES[@]}"; do
+ local actual
+
+ actual=$(ns_get_mode "${mode}0")
+ if [[ "${actual}" != "${mode}" ]]; then
+ log_host "expected mode ${mode}, got ${actual}"
+ return "${KSFT_FAIL}"
+ fi
+ done
+
+ return "${KSFT_PASS}"
+}
+
+test_ns_host_vsock_child_ns_mode_ok() {
+ local orig_mode
+ local rc
+
+ orig_mode=$(cat /proc/sys/net/vsock/child_ns_mode)
+
+ rc="${KSFT_PASS}"
+ for mode in "${NS_MODES[@]}"; do
+ local ns="${mode}0"
+
+ if echo "${mode}" 2>/dev/null > /proc/sys/net/vsock/ns_mode; then
+ log_host "ns_mode should be read-only but write succeeded"
+ rc="${KSFT_FAIL}"
+ continue
+ fi
+
+ if ! echo "${mode}" > /proc/sys/net/vsock/child_ns_mode; then
+ log_host "child_ns_mode should be writable to ${mode}"
+ rc="${KSFT_FAIL}"
+ continue
+ fi
+ done
+
+ echo "${orig_mode}" > /proc/sys/net/vsock/child_ns_mode
+
+ return "${rc}"
+}
+
test_vm_server_host_client() {
if ! vm_vsock_test "init_ns" "server" 2 "${TEST_GUEST_PORT}"; then
return "${KSFT_FAIL}"
@@ -592,6 +678,11 @@ run_shared_vm_tests() {
continue
fi

+ if ! check_netns "${arg}"; then
+ check_result "${KSFT_SKIP}" "${arg}"
+ continue
+ fi
+
run_shared_vm_test "${arg}"
check_result "$?" "${arg}"
done
@@ -645,6 +736,49 @@ run_shared_vm_test() {
return "${rc}"
}

+run_ns_tests() {
+ for arg in "${ARGS[@]}"; do
+ if shared_vm_test "${arg}"; then
+ continue
+ fi
+
+ if ! check_netns "${arg}"; then
+ check_result "${KSFT_SKIP}" "${arg}"
+ continue
+ fi
+
+ add_namespaces
+
+ name=$(echo "${arg}" | awk '{ print $1 }')
+ log_host "Executing test_${name}"
+
+ host_oops_before=$(dmesg 2>/dev/null | grep -c -i 'Oops')
+ host_warn_before=$(dmesg --level=warn 2>/dev/null | grep -c -i 'vsock')
+ eval test_"${name}"
+ rc=$?
+
+ host_oops_after=$(dmesg 2>/dev/null | grep -c -i 'Oops')
+ if [[ "${host_oops_after}" -gt "${host_oops_before}" ]]; then
+ echo "FAIL: kernel oops detected on host" | log_host
+ check_result "${KSFT_FAIL}" "${name}"
+ del_namespaces
+ continue
+ fi
+
+ host_warn_after=$(dmesg --level=warn 2>/dev/null | grep -c -i 'vsock')
+ if [[ "${host_warn_after}" -gt "${host_warn_before}" ]]; then
+ echo "FAIL: kernel warning detected on host" | log_host
+ check_result "${KSFT_FAIL}" "${name}"
+ del_namespaces
+ continue
+ fi
+
+ check_result "${rc}" "${name}"
+
+ del_namespaces
+ done
+}
+
BUILD=0
QEMU="qemu-system-$(uname -m)"

@@ -690,6 +824,8 @@ if shared_vm_tests_requested "${ARGS[@]}"; then
terminate_pidfiles "${pidfile}"
fi

+run_ns_tests "${ARGS[@]}"
+
echo "SUMMARY: PASS=${cnt_pass} SKIP=${cnt_skip} FAIL=${cnt_fail}"
echo "Log: ${LOG}"

--
2.47.3