[PATCH net-next v14 03/12] vsock: add netns support to virtio transports

13 Jan 2026

From: Bobby Eshleman bobbyeshleman@meta.com
Add netns support to loopback and vhost. Keep netns disabled for
virtio-vsock, but add necessary changes to comply with common API
updates.
This is the patch in the series when vhost-vsock namespaces actually
come online.
Signed-off-by: Bobby Eshleman bobbyeshleman@meta.com
---
Changes in v14:
- fixed merge conflicts in drivers/vhost/vsock.c
Changes in v13:
- do not store or pass the mode around now that net->vsock.mode is
  immutable
- move virtio_transport_stream_allow() into virtio_transport.c
  because virtio is the only caller now
Changes in v12:
- change seqpacket_allow() and stream_allow() to return true for
  loopback and vhost (Stefano)
Changes in v11:
- reorder with the skb ownership patch for loopback (Stefano)
- toggle vhost_transport_supports_local_mode() to true
Changes in v10:
- Splitting patches complicates the series with meaningless placeholder
  values that eventually get replaced anyway, so to avoid that this
  patch combines into one. Links to previous patches here:
  - Link: https://lore.kernel.org/all/20251111-vsock-vmtest-v9-3-852787a37bed@meta.com...
  - Link: https://lore.kernel.org/all/20251111-vsock-vmtest-v9-6-852787a37bed@meta.com...
  - Link: https://lore.kernel.org/all/20251111-vsock-vmtest-v9-7-852787a37bed@meta.com...
- remove placeholder values (Stefano)
- update comment describe net/net_mode for
  virtio_transport_reset_no_sock()
---
 drivers/vhost/vsock.c                   | 38 ++++++++++++++++-------
 include/linux/virtio_vsock.h            |  5 +--
 net/vmw_vsock/virtio_transport.c        | 13 ++++++--
 net/vmw_vsock/virtio_transport_common.c | 54 +++++++++++++++++++--------------
 net/vmw_vsock/vsock_loopback.c          | 14 +++++++--
 5 files changed, 84 insertions(+), 40 deletions(-)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 647ded6f6ea5..488d7fa6e4ec 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -48,6 +48,8 @@ static DEFINE_READ_MOSTLY_HASHTABLE(vhost_vsock_hash, 8);
 struct vhost_vsock {
    struct vhost_dev dev;
    struct vhost_virtqueue vqs[2];
+	struct net *net;
+	netns_tracker ns_tracker;
/* Link to global vhost_vsock_hash, writes use vhost_vsock_mutex */
    struct hlist_node hash;
@@ -69,7 +71,7 @@ static u32 vhost_transport_get_local_cid(void)
 /* Callers must be in an RCU read section or hold the vhost_vsock_mutex.
  * The return value can only be dereferenced while within the section.
  */
-static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
+static struct vhost_vsock *vhost_vsock_get(u32 guest_cid, struct net *net)
 {
    struct vhost_vsock *vsock;
@@ -81,9 +83,9 @@ static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
    	if (other_cid == 0)
    		continue;
-		if (other_cid == guest_cid)
+		if (other_cid == guest_cid &&
+		    vsock_net_check_mode(net, vsock->net))
    		return vsock;
-
    }
return NULL;
@@ -272,7 +274,7 @@ static void vhost_transport_send_pkt_work(struct vhost_work *work)
 }
static int
-vhost_transport_send_pkt(struct sk_buff *skb)
+vhost_transport_send_pkt(struct sk_buff *skb, struct net *net)
 {
    struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
    struct vhost_vsock *vsock;
@@ -281,7 +283,7 @@ vhost_transport_send_pkt(struct sk_buff *skb)
    rcu_read_lock();
/* Find the vhost_vsock according to guest context id  */
-	vsock = vhost_vsock_get(le64_to_cpu(hdr->dst_cid));
+	vsock = vhost_vsock_get(le64_to_cpu(hdr->dst_cid), net);
    if (!vsock) {
    	rcu_read_unlock();
    	kfree_skb(skb);
@@ -308,7 +310,8 @@ vhost_transport_cancel_pkt(struct vsock_sock *vsk)
    rcu_read_lock();
/* Find the vhost_vsock according to guest context id  */
-	vsock = vhost_vsock_get(vsk->remote_addr.svm_cid);
+	vsock = vhost_vsock_get(vsk->remote_addr.svm_cid,
+				sock_net(sk_vsock(vsk)));
    if (!vsock)
    	goto out;
@@ -410,6 +413,12 @@ static bool vhost_transport_msgzerocopy_allow(void)
 static bool vhost_transport_seqpacket_allow(struct vsock_sock *vsk,
    				    u32 remote_cid);
+static bool
+vhost_transport_stream_allow(struct vsock_sock *vsk, u32 cid, u32 port)
+{
+	return true;
+}
+
 static struct virtio_transport vhost_transport = {
    .transport = {
    	.module                   = THIS_MODULE,
@@ -434,7 +443,7 @@ static struct virtio_transport vhost_transport = {
    	.stream_has_space         = virtio_transport_stream_has_space,
    	.stream_rcvhiwat          = virtio_transport_stream_rcvhiwat,
    	.stream_is_active         = virtio_transport_stream_is_active,
-		.stream_allow             = virtio_transport_stream_allow,
+		.stream_allow             = vhost_transport_stream_allow,
.seqpacket_dequeue        = virtio_transport_seqpacket_dequeue,
    	.seqpacket_enqueue        = virtio_transport_seqpacket_enqueue,
@@ -467,11 +476,12 @@ static struct virtio_transport vhost_transport = {
 static bool vhost_transport_seqpacket_allow(struct vsock_sock *vsk,
    				    u32 remote_cid)
 {
+	struct net *net = sock_net(sk_vsock(vsk));
    struct vhost_vsock *vsock;
    bool seqpacket_allow = false;
rcu_read_lock();
-	vsock = vhost_vsock_get(remote_cid);
+	vsock = vhost_vsock_get(remote_cid, net);
if (vsock)
    	seqpacket_allow = vsock->seqpacket_allow;
@@ -542,7 +552,8 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
    	if (le64_to_cpu(hdr->src_cid) == vsock->guest_cid &&
    	    le64_to_cpu(hdr->dst_cid) ==
    	    vhost_transport_get_local_cid())
-			virtio_transport_recv_pkt(&vhost_transport, skb);
+			virtio_transport_recv_pkt(&vhost_transport, skb,
+						  vsock->net);
    	else
    		kfree_skb(skb);
@@ -659,6 +670,7 @@ static int vhost_vsock_dev_open(struct inode *inode, struct file *file)
 {
    struct vhost_virtqueue **vqs;
    struct vhost_vsock *vsock;
+	struct net *net;
    int ret;
/* This struct is large and allocation could fail, fall back to vmalloc
@@ -674,6 +686,9 @@ 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);
+
    vsock->guest_cid = 0; /* no CID assigned yet */
    vsock->seqpacket_allow = false;
@@ -715,7 +730,7 @@ static void vhost_vsock_reset_orphans(struct sock *sk)
    rcu_read_lock();
/* If the peer is still valid, no need to reset connection */
-	if (vhost_vsock_get(vsk->remote_addr.svm_cid)) {
+	if (vhost_vsock_get(vsk->remote_addr.svm_cid, sock_net(sk))) {
    	rcu_read_unlock();
    	return;
    }
@@ -764,6 +779,7 @@ static int vhost_vsock_dev_release(struct inode *inode, struct file *file)
    virtio_vsock_skb_queue_purge(&vsock->send_pkt_queue);
vhost_dev_cleanup(&vsock->dev);
+	put_net_track(vsock->net, &vsock->ns_tracker);
    kfree(vsock->dev.vqs);
    vhost_vsock_free(vsock);
    return 0;
@@ -790,7 +806,7 @@ static int vhost_vsock_set_cid(struct vhost_vsock *vsock, u64 guest_cid)
/* Refuse if CID is already in use */
    mutex_lock(&vhost_vsock_mutex);
-	other = vhost_vsock_get(guest_cid);
+	other = vhost_vsock_get(guest_cid, vsock->net);
    if (other && other != vsock) {
    	mutex_unlock(&vhost_vsock_mutex);
    	return -EADDRINUSE;
diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 1845e8d4f78d..f91704731057 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -173,6 +173,7 @@ struct virtio_vsock_pkt_info {
    u32 remote_cid, remote_port;
    struct vsock_sock *vsk;
    struct msghdr *msg;
+	struct net *net;
    u32 pkt_len;
    u16 type;
    u16 op;
@@ -185,7 +186,7 @@ struct virtio_transport {
    struct vsock_transport transport;
/* Takes ownership of the packet */
-	int (*send_pkt)(struct sk_buff *skb);
+	int (*send_pkt)(struct sk_buff *skb, struct net *net);
/* Used in MSG_ZEROCOPY mode. Checks, that provided data
     * (number of buffers) could be transmitted with zerocopy
@@ -280,7 +281,7 @@ virtio_transport_dgram_enqueue(struct vsock_sock *vsk,
 void virtio_transport_destruct(struct vsock_sock *vsk);
void virtio_transport_recv_pkt(struct virtio_transport *t,
-			       struct sk_buff *skb);
+			       struct sk_buff *skb, struct net *net);
 void virtio_transport_inc_tx_pkt(struct virtio_vsock_sock *vvs, struct sk_buff *skb);
 u32 virtio_transport_get_credit(struct virtio_vsock_sock *vvs, u32 wanted);
 void virtio_transport_put_credit(struct virtio_vsock_sock *vvs, u32 credit);
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index 37eeefddb48c..22ff5a503070 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -231,7 +231,7 @@ static int virtio_transport_send_skb_fast_path(struct virtio_vsock *vsock, struc
 }
static int
-virtio_transport_send_pkt(struct sk_buff *skb)
+virtio_transport_send_pkt(struct sk_buff *skb, struct net *net)
 {
    struct virtio_vsock_hdr *hdr;
    struct virtio_vsock *vsock;
@@ -536,6 +536,11 @@ static bool virtio_transport_msgzerocopy_allow(void)
    return true;
 }
+bool virtio_transport_stream_allow(struct vsock_sock *vsk, u32 cid, u32 port)
+{
+	return vsock_net_mode(sock_net(sk_vsock(vsk))) == VSOCK_NET_MODE_GLOBAL;
+}
+
 static bool virtio_transport_seqpacket_allow(struct vsock_sock *vsk,
    				     u32 remote_cid);
@@ -665,7 +670,11 @@ static void virtio_transport_rx_work(struct work_struct *work)
    			virtio_vsock_skb_put(skb, payload_len);
virtio_transport_deliver_tap_pkt(skb);
-			virtio_transport_recv_pkt(&virtio_transport, skb);
+
+			/* Force virtio-transport into global mode since it
+			 * does not yet support local-mode namespacing.
+			 */
+			virtio_transport_recv_pkt(&virtio_transport, skb, NULL);
    	}
    } while (!virtqueue_enable_cb(vq));
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 718be9f33274..c126aa235091 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -413,7 +413,7 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
virtio_transport_inc_tx_pkt(vvs, skb);
-		ret = t_ops->send_pkt(skb);
+		ret = t_ops->send_pkt(skb, info->net);
    	if (ret < 0)
    		break;
@@ -527,6 +527,7 @@ static int virtio_transport_send_credit_update(struct vsock_sock *vsk)
    struct virtio_vsock_pkt_info info = {
    	.op = VIRTIO_VSOCK_OP_CREDIT_UPDATE,
    	.vsk = vsk,
+		.net = sock_net(sk_vsock(vsk)),
    };
return virtio_transport_send_pkt_info(vsk, &info);
@@ -1043,12 +1044,6 @@ bool virtio_transport_stream_is_active(struct vsock_sock *vsk)
 }
 EXPORT_SYMBOL_GPL(virtio_transport_stream_is_active);
-bool virtio_transport_stream_allow(struct vsock_sock *vsk, u32 cid, u32 port)
-{
-	return vsock_net_mode(sock_net(sk_vsock(vsk))) == VSOCK_NET_MODE_GLOBAL;
-}
-EXPORT_SYMBOL_GPL(virtio_transport_stream_allow);
-
 int virtio_transport_dgram_bind(struct vsock_sock *vsk,
    			struct sockaddr_vm *addr)
 {
@@ -1067,6 +1062,7 @@ int virtio_transport_connect(struct vsock_sock *vsk)
    struct virtio_vsock_pkt_info info = {
    	.op = VIRTIO_VSOCK_OP_REQUEST,
    	.vsk = vsk,
+		.net = sock_net(sk_vsock(vsk)),
    };
return virtio_transport_send_pkt_info(vsk, &info);
@@ -1082,6 +1078,7 @@ int virtio_transport_shutdown(struct vsock_sock *vsk, int mode)
    		 (mode & SEND_SHUTDOWN ?
    		  VIRTIO_VSOCK_SHUTDOWN_SEND : 0),
    	.vsk = vsk,
+		.net = sock_net(sk_vsock(vsk)),
    };
return virtio_transport_send_pkt_info(vsk, &info);
@@ -1108,6 +1105,7 @@ virtio_transport_stream_enqueue(struct vsock_sock *vsk,
    	.msg = msg,
    	.pkt_len = len,
    	.vsk = vsk,
+		.net = sock_net(sk_vsock(vsk)),
    };
return virtio_transport_send_pkt_info(vsk, &info);
@@ -1145,6 +1143,7 @@ static int virtio_transport_reset(struct vsock_sock *vsk,
    	.op = VIRTIO_VSOCK_OP_RST,
    	.reply = !!skb,
    	.vsk = vsk,
+		.net = sock_net(sk_vsock(vsk)),
    };
/* Send RST only if the original pkt is not a RST pkt */
@@ -1156,9 +1155,13 @@ static int virtio_transport_reset(struct vsock_sock *vsk,
/* Normally packets are associated with a socket.  There may be no socket if an
  * attempt was made to connect to a socket that does not exist.
+ *
+ * net refers to the namespace of whoever sent the invalid message. For
+ * loopback, this is the namespace of the socket. For vhost, this is the
+ * namespace of the VM (i.e., vhost_vsock).
  */
 static int virtio_transport_reset_no_sock(const struct virtio_transport *t,
-					  struct sk_buff *skb)
+					  struct sk_buff *skb, struct net *net)
 {
    struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
    struct virtio_vsock_pkt_info info = {
@@ -1171,6 +1174,12 @@ static int virtio_transport_reset_no_sock(const struct virtio_transport *t,
    	 * sock_net(sk) until the reply skb is freed.
    	 */
    	.vsk = vsock_sk(skb->sk),
+
+		/* net is not defined here because we pass it directly to
+		 * t->send_pkt(), instead of relying on
+		 * virtio_transport_send_pkt_info() to pass it. It is not needed
+		 * by virtio_transport_alloc_skb().
+		 */
    };
    struct sk_buff *reply;
@@ -1189,7 +1198,7 @@ static int virtio_transport_reset_no_sock(const struct virtio_transport *t,
    if (!reply)
    	return -ENOMEM;
-	return t->send_pkt(reply);
+	return t->send_pkt(reply, net);
 }
/* This function should be called with sk_lock held and SOCK_DONE set */
@@ -1471,6 +1480,7 @@ virtio_transport_send_response(struct vsock_sock *vsk,
    	.remote_port = le32_to_cpu(hdr->src_port),
    	.reply = true,
    	.vsk = vsk,
+		.net = sock_net(sk_vsock(vsk)),
    };
return virtio_transport_send_pkt_info(vsk, &info);
@@ -1513,12 +1523,12 @@ virtio_transport_recv_listen(struct sock *sk, struct sk_buff *skb,
    int ret;
if (le16_to_cpu(hdr->op) != VIRTIO_VSOCK_OP_REQUEST) {
-		virtio_transport_reset_no_sock(t, skb);
+		virtio_transport_reset_no_sock(t, skb, sock_net(sk));
    	return -EINVAL;
    }
if (sk_acceptq_is_full(sk)) {
-		virtio_transport_reset_no_sock(t, skb);
+		virtio_transport_reset_no_sock(t, skb, sock_net(sk));
    	return -ENOMEM;
    }
@@ -1526,13 +1536,13 @@ virtio_transport_recv_listen(struct sock *sk, struct sk_buff *skb,
     * Subsequent enqueues would lead to a memory leak.
     */
    if (sk->sk_shutdown == SHUTDOWN_MASK) {
-		virtio_transport_reset_no_sock(t, skb);
+		virtio_transport_reset_no_sock(t, skb, sock_net(sk));
    	return -ESHUTDOWN;
    }
child = vsock_create_connected(sk);
    if (!child) {
-		virtio_transport_reset_no_sock(t, skb);
+		virtio_transport_reset_no_sock(t, skb, sock_net(sk));
    	return -ENOMEM;
    }
@@ -1554,7 +1564,7 @@ virtio_transport_recv_listen(struct sock *sk, struct sk_buff *skb,
     */
    if (ret || vchild->transport != &t->transport) {
    	release_sock(child);
-		virtio_transport_reset_no_sock(t, skb);
+		virtio_transport_reset_no_sock(t, skb, sock_net(sk));
    	sock_put(child);
    	return ret;
    }
@@ -1582,7 +1592,7 @@ static bool virtio_transport_valid_type(u16 type)
  * lock.
  */
 void virtio_transport_recv_pkt(struct virtio_transport *t,
-			       struct sk_buff *skb)
+			       struct sk_buff *skb, struct net *net)
 {
    struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
    struct sockaddr_vm src, dst;
@@ -1605,24 +1615,24 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
    				le32_to_cpu(hdr->fwd_cnt));
if (!virtio_transport_valid_type(le16_to_cpu(hdr->type))) {
-		(void)virtio_transport_reset_no_sock(t, skb);
+		(void)virtio_transport_reset_no_sock(t, skb, net);
    	goto free_pkt;
    }
/* The socket must be in connected or bound table
     * otherwise send reset back
     */
-	sk = vsock_find_connected_socket(&src, &dst);
+	sk = vsock_find_connected_socket_net(&src, &dst, net);
    if (!sk) {
-		sk = vsock_find_bound_socket(&dst);
+		sk = vsock_find_bound_socket_net(&dst, net);
    	if (!sk) {
-			(void)virtio_transport_reset_no_sock(t, skb);
+			(void)virtio_transport_reset_no_sock(t, skb, net);
    		goto free_pkt;
    	}
    }
if (virtio_transport_get_type(sk) != le16_to_cpu(hdr->type)) {
-		(void)virtio_transport_reset_no_sock(t, skb);
+		(void)virtio_transport_reset_no_sock(t, skb, net);
    	sock_put(sk);
    	goto free_pkt;
    }
@@ -1641,7 +1651,7 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
     */
    if (sock_flag(sk, SOCK_DONE) ||
        (sk->sk_state != TCP_LISTEN && vsk->transport != &t->transport)) {
-		(void)virtio_transport_reset_no_sock(t, skb);
+		(void)virtio_transport_reset_no_sock(t, skb, net);
    	release_sock(sk);
    	sock_put(sk);
    	goto free_pkt;
@@ -1673,7 +1683,7 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
    	kfree_skb(skb);
    	break;
    default:
-		(void)virtio_transport_reset_no_sock(t, skb);
+		(void)virtio_transport_reset_no_sock(t, skb, net);
    	kfree_skb(skb);
    	break;
    }
diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c
index 378a96dcb666..dbd4d81e0acb 100644
--- a/net/vmw_vsock/vsock_loopback.c
+++ b/net/vmw_vsock/vsock_loopback.c
@@ -26,7 +26,7 @@ static u32 vsock_loopback_get_local_cid(void)
    return VMADDR_CID_LOCAL;
 }
-static int vsock_loopback_send_pkt(struct sk_buff *skb)
+static int vsock_loopback_send_pkt(struct sk_buff *skb, struct net *net)
 {
    struct vsock_loopback *vsock = &the_vsock_loopback;
    int len = skb->len;
@@ -48,6 +48,13 @@ static int vsock_loopback_cancel_pkt(struct vsock_sock *vsk)
static bool vsock_loopback_seqpacket_allow(struct vsock_sock *vsk,
    				   u32 remote_cid);
+
+static bool vsock_loopback_stream_allow(struct vsock_sock *vsk, u32 cid,
+					u32 port)
+{
+	return true;
+}
+
 static bool vsock_loopback_msgzerocopy_allow(void)
 {
    return true;
@@ -77,7 +84,7 @@ static struct virtio_transport loopback_transport = {
    	.stream_has_space         = virtio_transport_stream_has_space,
    	.stream_rcvhiwat          = virtio_transport_stream_rcvhiwat,
    	.stream_is_active         = virtio_transport_stream_is_active,
-		.stream_allow             = virtio_transport_stream_allow,
+		.stream_allow             = vsock_loopback_stream_allow,
.seqpacket_dequeue        = virtio_transport_seqpacket_dequeue,
    	.seqpacket_enqueue        = virtio_transport_seqpacket_enqueue,
@@ -132,7 +139,8 @@ static void vsock_loopback_work(struct work_struct *work)
    	 */
    	virtio_transport_consume_skb_sent(skb, false);
    	virtio_transport_deliver_tap_pkt(skb);
-		virtio_transport_recv_pkt(&loopback_transport, skb);
+		virtio_transport_recv_pkt(&loopback_transport, skb,
+					  sock_net(skb->sk));
    }
 }
-- 
2.47.3



    

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[PATCH net-next v14 03/12] vsock: add netns support to virtio transports