From: Bobby Eshleman <bobbyeshleman@meta.com>

Add functions for initializing namespaces with the different vsock NS
modes. Callers can use add_namespaces() and del_namespaces() to create
namespaces global0, global1, local0, and local1.

The add_namespaces() function initializes global0, local0, etc... with
their respective vsock NS mode by toggling child_ns_mode before creating
the namespace.

Remove namespaces upon exiting the program in cleanup(). This is
unlikely to be needed for a healthy run, but it is useful for tests that
are manually killed mid-test.

This patch is in preparation for later namespace tests.

Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
---
Changes in v13:
- intialize namespaces to use the child_ns_mode mechanism
- remove setting modes from init_namespaces() function (this function
  only sets up the lo device now)
- remove ns_set_mode(ns) because ns_mode is no longer mutable
---
 tools/testing/selftests/vsock/vmtest.sh | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/tools/testing/selftests/vsock/vmtest.sh b/tools/testing/selftests/vsock/vmtest.sh
index c7b270dd77a9..c2bdc293b94c 100755
--- a/tools/testing/selftests/vsock/vmtest.sh
+++ b/tools/testing/selftests/vsock/vmtest.sh
@@ -49,6 +49,7 @@ readonly TEST_DESCS=(
 )
 
 readonly USE_SHARED_VM=(vm_server_host_client vm_client_host_server vm_loopback)
+readonly NS_MODES=("local" "global")
 
 VERBOSE=0
 
@@ -103,6 +104,36 @@ check_result() {
 	fi
 }
 
+add_namespaces() {
+	local orig_mode
+	orig_mode=$(cat /proc/sys/net/vsock/child_ns_mode)
+
+	for mode in "${NS_MODES[@]}"; do
+		echo "${mode}" > /proc/sys/net/vsock/child_ns_mode
+		ip netns add "${mode}0" 2>/dev/null
+		ip netns add "${mode}1" 2>/dev/null
+	done
+
+	echo "${orig_mode}" > /proc/sys/net/vsock/child_ns_mode
+}
+
+init_namespaces() {
+	for mode in "${NS_MODES[@]}"; do
+		# we need lo for qemu port forwarding
+		ip netns exec "${mode}0" ip link set dev lo up
+		ip netns exec "${mode}1" ip link set dev lo up
+	done
+}
+
+del_namespaces() {
+	for mode in "${NS_MODES[@]}"; do
+		ip netns del "${mode}0" &>/dev/null
+		ip netns del "${mode}1" &>/dev/null
+		log_host "removed ns ${mode}0"
+		log_host "removed ns ${mode}1"
+	done
+}
+
 vm_ssh() {
 	ssh -q -o UserKnownHostsFile=/dev/null -p ${SSH_HOST_PORT} localhost "$@"
 	return $?
@@ -110,6 +141,7 @@ vm_ssh() {
 
 cleanup() {
 	terminate_pidfiles "${!PIDFILES[@]}"
+	del_namespaces
 }
 
 check_args() {

-- 
2.47.3