Re: [PATCH net-next v10 08/11] selftests/vsock: add tests for proc sys vsock ns_mode

On Mon, Nov 17, 2025 at 06:00:31PM -0800, Bobby Eshleman wrote:

From: Bobby Eshleman bobbyeshleman@meta.com

Add tests for the /proc/sys/net/vsock/ns_mode interface. Namely, that it accepts "global" and "local" strings and enforces a write-once policy.

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.

Add a test to verify that guest VMs with an active G2H transport (virtio-vsock) cannot set namespace mode to 'local'. This validates the mutual exclusion between G2H transports and LOCAL mode.

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

Signed-off-by: Bobby Eshleman bobbyeshleman@meta.com

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 1a7c810f282f..86483249f490 100755 --- a/tools/testing/selftests/vsock/vmtest.sh +++ b/tools/testing/selftests/vsock/vmtest.sh @@ -41,14 +41,40 @@ 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) +readonly TEST_NAMES=(

• vm_server_host_client
• vm_client_host_server
• vm_loopback
• ns_host_vsock_ns_mode_ok
• ns_host_vsock_ns_mode_write_once_ok
• ns_vm_local_mode_rejected

+) 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_ns_mode_write_once_ok
• "Check /proc/sys/net/vsock/ns_mode is write-once on the host."
• # ns_vm_local_mode_rejected
• "Test that guest VM with G2H transport cannot set namespace mode to 'local'"

)

-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
• ns_vm_local_mode_rejected

+) readonly NS_MODES=("local" "global")

VERBOSE=0 @@ -205,6 +231,20 @@ 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_ ]] &&

If check_netns() is based on the test name, IMO we should document that on top of TEST_NAMES.

Thanks, Stefano

•   [[ ! -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 @@ -503,6 +543,32 @@ log_guest() { LOG_PREFIX=guest log "$@" }

+test_ns_host_vsock_ns_mode_ok() {

• for mode in "${NS_MODES[@]}"; do

• if ! ns_set_mode "${mode}0" "${mode}"; then
  

• 	return "${KSFT_FAIL}"
  

• fi
  

• done
• return "${KSFT_PASS}"

+}

+test_ns_host_vsock_ns_mode_write_once_ok() {

• for mode in "${NS_MODES[@]}"; do

• local ns="${mode}0"
  

• if ! ns_set_mode "${ns}" "${mode}"; then
  

• 	return "${KSFT_FAIL}"
  

• fi
  

• # try writing again and expect failure
  

• if ns_set_mode "${ns}" "${mode}"; then
  

• 	return "${KSFT_FAIL}"
  

• fi
  

• done
• return "${KSFT_PASS}"

+}

test_vm_server_host_client() { if ! vm_vsock_test "init_ns" "server" 2 "${TEST_GUEST_PORT}"; then return "${KSFT_FAIL}" @@ -544,6 +610,26 @@ test_vm_loopback() { return "${KSFT_PASS}" }

+test_ns_vm_local_mode_rejected() {

• # Guest VMs have a G2H transport (virtio-vsock) active, so they
• # should not be able to set namespace mode to 'local'.
• # This test verifies that the sysctl write fails as expected.
• # Try to set local mode in the guest's init_ns
• if vm_ssh init_ns "echo local | tee /proc/sys/net/vsock/ns_mode &>/dev/null"; then

• return "${KSFT_FAIL}"
  

• fi
• # Verify mode is still 'global'
• local mode
• mode=$(vm_ssh init_ns "cat /proc/sys/net/vsock/ns_mode")
• if [[ "${mode}" != "global" ]]; then

• return "${KSFT_FAIL}"
  

• fi
• return "${KSFT_PASS}"

+}

shared_vm_test() { local tname

@@ -576,6 +662,11 @@ 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

@@ -629,6 +720,49 @@ 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)"

@@ -674,6 +808,8 @@ 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