On Mon, Jan 12, 2026 at 03:34:31PM -0800, Bobby Eshleman wrote:
> On Sun, Jan 11, 2026 at 01:43:37AM -0500, Michael S. Tsirkin wrote:
> > On Tue, Dec 23, 2025 at 04:28:36PM -0800, Bobby Eshleman wrote:
> > > From: Bobby Eshleman <[email protected]>
> > >
> > > Add netns logic to vsock core. Additionally, modify transport hook
> > > prototypes to be used by later transport-specific patches (e.g.,
> > > *_seqpacket_allow()).
> > >
> > > Namespaces are supported primarily by changing socket lookup functions
> > > (e.g., vsock_find_connected_socket()) to take into account the socket
> > > namespace and the namespace mode before considering a candidate socket a
> > > "match".
> > >
> > > This patch also introduces the sysctl /proc/sys/net/vsock/ns_mode to
> > > report the mode and /proc/sys/net/vsock/child_ns_mode to set the mode
> > > for new namespaces.
> > >
> > > Add netns functionality (initialization, passing to transports, procfs,
> > > etc...) to the af_vsock socket layer. Later patches that add netns
> > > support to transports depend on this patch.
> > >
> > > dgram_allow(), stream_allow(), and seqpacket_allow() callbacks are
> > > modified to take a vsk in order to perform logic on namespace modes. In
> > > future patches, the net will also be used for socket
> > > lookups in these functions.
> > >
> > > Signed-off-by: Bobby Eshleman <[email protected]>
> >
> > ...
> >
> >
> > > static int __vsock_bind_connectible(struct vsock_sock *vsk,
> > > struct sockaddr_vm *addr)
> > > {
> > > + struct net *net = sock_net(sk_vsock(vsk));
> > > static u32 port;
> > > struct sockaddr_vm new_addr;
> > >
> >
> >
> > Hmm this static port gives me pause. So some port number info leaks
> > between namespaces. I am not saying it's a big security issue
> > and yet ... people expect isolation.
>
> Probably the easiest solution is making it per-ns, my quick rough draft
> looks like this:
Sounds like a plan.
> diff --git a/include/net/netns/vsock.h b/include/net/netns/vsock.h
> index e2325e2d6ec5..b34d69a22fa8 100644
> --- a/include/net/netns/vsock.h
> +++ b/include/net/netns/vsock.h
> @@ -11,6 +11,10 @@ enum vsock_net_mode {
>
> struct netns_vsock {
> struct ctl_table_header *sysctl_hdr;
> +
> + /* protected by the vsock_table_lock in af_vsock.c */
> + u32 port;
> +
> enum vsock_net_mode mode;
> enum vsock_net_mode child_ns_mode;
> };
> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> index 9d614e4a4fa5..cd2a47140134 100644
> --- a/net/vmw_vsock/af_vsock.c
> +++ b/net/vmw_vsock/af_vsock.c
> @@ -748,11 +748,10 @@ static int __vsock_bind_connectible(struct vsock_sock
> *vsk,
> struct sockaddr_vm *addr)
> {
> struct net *net = sock_net(sk_vsock(vsk));
> - static u32 port;
> struct sockaddr_vm new_addr;
>
> - if (!port)
> - port = get_random_u32_above(LAST_RESERVED_PORT);
> + if (!net->vsock.port)
> + net->vsock.port = get_random_u32_above(LAST_RESERVED_PORT);
>
> vsock_addr_init(&new_addr, addr->svm_cid, addr->svm_port);
>
> @@ -761,11 +760,11 @@ static int __vsock_bind_connectible(struct vsock_sock
> *vsk,
> unsigned int i;
>
> for (i = 0; i < MAX_PORT_RETRIES; i++) {
> - if (port == VMADDR_PORT_ANY ||
> - port <= LAST_RESERVED_PORT)
> - port = LAST_RESERVED_PORT + 1;
> + if (net->vsock.port == VMADDR_PORT_ANY ||
> + net->vsock.port <= LAST_RESERVED_PORT)
> + net->vsock.port = LAST_RESERVED_PORT + 1;
>
> - new_addr.svm_port = port++;
> + new_addr.svm_port = net->vsock.port++;
>
> if (!__vsock_find_bound_socket_net(&new_addr, net)) {
> found = true;
>
>
>
> Not as nice, but not necessarily horrid. WDYT?
>
> Best,
> Bobby
I wouldn't call static vars "nice". LGTM.
