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_ ]] &&
+	   [[ ! -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

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
>