On Tue, Dec 02, 2025 at 11:18:14AM +0100, Paolo Abeni wrote:
On 11/27/25 8:47 AM, Bobby Eshleman wrote:
@@ -674,6 +689,17 @@ static int vhost_vsock_dev_open(struct inode *inode, struct file *file) goto out; }
- net = current->nsproxy->net_ns;
- vsock->net = get_net_track(net, &vsock->ns_tracker, GFP_KERNEL);
- /* Store the mode of the namespace at the time of creation. If this
* namespace later changes from "global" to "local", we want this vsock* to continue operating normally and not suddenly break. For that* reason, we save the mode here and later use it when performing* socket lookups with vsock_net_check_mode() (see vhost_vsock_get()).*/- vsock->net_mode = vsock_net_mode(net);
I'm sorry for the very late feedback. I think that at very least the user-space needs a way to query if the given transport is in local or global mode, as AFAICS there is no way to tell that when socket creation races with mode change.
Are you thinking something along the lines of sockopt?
Also I'm a bit uneasy with the model implemented here, as 'local' socket may cross netns boundaris and connect to 'local' socket in other netns (if I read correctly patch 2/12). That in turns AFAICS break the netns isolation.
Local mode sockets are unable to communicate with local mode (and global mode too) sockets that are in other namespaces. The key piece of code for that is vsock_net_check_mode(), where if either modes is local the namespaces must be the same.
Have you considered instead a slightly different model, where the local/global model is set in stone at netns creation time - alike what /proc/sys/net/ipv4/tcp_child_ehash_entries is doing[1] - and inter-netns connectivity is explicitly granted by the admin (I guess you will need new transport operations for that)?
/P
[1] tcp allows using per-netns established socket lookup tables - as opposed to the default global lookup table (even if match always takes in account the netns obviously). The mentioned sysctl specify such configuration for the children namespaces, if any.
I'll save this discussion if the above doesn't resolve your concerns.
Best, Bobby