Message-Id: <20251111-vsock-vmtest-v9-11-852787a37bed@meta.com>
Date: Tue, 11 Nov 2025 22:54:53 -0800
From: Bobby Eshleman <bobbyeshleman@...il.com>
To: Stefano Garzarella <sgarzare@...hat.com>, Shuah Khan <shuah@...nel.org>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Simon Horman <horms@...nel.org>, Stefan Hajnoczi <stefanha@...hat.com>, 
 "Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, 
 Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, 
 Eugenio Pérez <eperezma@...hat.com>, 
 "K. Y. Srinivasan" <kys@...rosoft.com>, 
 Haiyang Zhang <haiyangz@...rosoft.com>, Wei Liu <wei.liu@...nel.org>, 
 Dexuan Cui <decui@...rosoft.com>, Bryan Tan <bryan-bt.tan@...adcom.com>, 
 Vishnu Dasa <vishnu.dasa@...adcom.com>, 
 Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>, 
 Bobby Eshleman <bobbyeshleman@...il.com>
Cc: virtualization@...ts.linux.dev, netdev@...r.kernel.org, 
 linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org, 
 kvm@...r.kernel.org, linux-hyperv@...r.kernel.org, 
 Sargun Dhillon <sargun@...gun.me>, berrange@...hat.com, 
 Bobby Eshleman <bobbyeshleman@...a.com>
Subject: [PATCH net-next v9 11/14] selftests/vsock: add tests for proc sys
 vsock ns_mode

From: Bobby Eshleman <bobbyeshleman@...a.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@...a.com>
---
Changes in v9:
- add test ns_vm_local_mode_rejected to check that guests cannot use
  local mode
---
 tools/testing/selftests/vsock/vmtest.sh | 130 +++++++++++++++++++++++++++++++-
 1 file changed, 128 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/vsock/vmtest.sh b/tools/testing/selftests/vsock/vmtest.sh
index 663be2da4e22..ef5f1d954f8b 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 ${tname}"
+		return 1
+	fi
+
+	return 0
+}
+
 check_vng() {
 	local tested_versions
 	local version
@@ -503,6 +543,43 @@ log_guest() {
 	LOG_PREFIX=guest log "$@"
 }
 
+test_ns_host_vsock_ns_mode_ok() {
+	add_namespaces
+
+	for mode in "${NS_MODES[@]}"; do
+		if ! ns_set_mode "${mode}0" "${mode}"; then
+			del_namespaces
+			return "${KSFT_FAIL}"
+		fi
+	done
+
+	del_namespaces
+
+	return "${KSFT_PASS}"
+}
+
+test_ns_host_vsock_ns_mode_write_once_ok() {
+	add_namespaces
+
+	for mode in "${NS_MODES[@]}"; do
+		local ns="${mode}0"
+		if ! ns_set_mode "${ns}" "${mode}"; then
+			del_namespaces
+			return "${KSFT_FAIL}"
+		fi
+
+		# try writing again and expect failure
+		if ns_set_mode "${ns}" "${mode}"; then
+			del_namespaces
+			return "${KSFT_FAIL}"
+		fi
+	done
+
+	del_namespaces
+
+	return "${KSFT_PASS}"
+}
+
 test_vm_server_host_client() {
 	if ! vm_vsock_test "init_ns" "server" 2 "${TEST_GUEST_PORT}"; then
 		return "${KSFT_FAIL}"
@@ -544,6 +621,26 @@ 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 +673,11 @@ 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 +731,28 @@ run_shared_vm_test() {
 	return "${rc}"
 }
 
+run_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}"
+		eval test_"${name}"
+		check_result $? "${name}"
+
+		del_namespaces
+	done
+}
+
 BUILD=0
 QEMU="qemu-system-$(uname -m)"
 
@@ -674,6 +798,8 @@ if shared_vm_tests_requested "${ARGS[@]}"; then
 	terminate_pidfiles "${pidfile}"
 fi
 
+run_tests "${ARGS[@]}"
+
 echo "SUMMARY: PASS=${cnt_pass} SKIP=${cnt_skip} FAIL=${cnt_fail}"
 echo "Log: ${LOG}"
 

-- 
2.47.3

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