From: Stefano Garzarella <sgarzare@redhat.com>

When a new network namespace is created, vsock_net_init() correctly
initializes the namespace's mode by reading the parent's `child_ns_mode`
via vsock_net_child_mode(). However, the `child_ns_mode` of the new
namespace was always hardcoded to VSOCK_NET_MODE_GLOBAL, regardless of
its own mode.

This means that if a parent namespace has `child_ns_mode` set to "local",
the child namespace correctly gets mode "local", but its `child_ns_mode`
is reset to "global". As a result, further nested namespaces will
incorrectly get mode "global" instead of inheriting "local", breaking
the expected propagation of the mode through nested namespaces.

Fix this by initializing `child_ns_mode` to the namespace's own mode,
so the setting propagates correctly through all levels of nesting.

Fixes: eafb64f40ca4 ("vsock: add netns to vsock core")
Cc: bobbyeshleman@meta.com
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
 net/vmw_vsock/af_vsock.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 20ad2b2dc17b..3b629b4a0359 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c

@@ -91,7 +91,8 @@
  *   - /proc/sys/net/vsock/ns_mode (read-only) reports the current namespace's
  *     mode, which is set at namespace creation and immutable thereafter.
  *   - /proc/sys/net/vsock/child_ns_mode (writable) controls what mode future
- *     child namespaces will inherit when created. The default is "global".
+ *     child namespaces will inherit when created. The initial value matches
+ *     the namespace's own ns_mode.
  *
  *   Changing child_ns_mode only affects newly created namespaces, not the
  *   current namespace or existing children. At namespace creation, ns_mode

@@ -2912,7 +2913,7 @@ static void vsock_net_init(struct net *net)
 	else
 		net->vsock.mode = vsock_net_child_mode(current->nsproxy->net_ns);
 
-	net->vsock.child_ns_mode = VSOCK_NET_MODE_GLOBAL;
+	net->vsock.child_ns_mode = net->vsock.mode;
 }
 
 static __net_init int vsock_sysctl_init_net(struct net *net)

-- 
2.53.0