On Thu, Nov 20, 2025 at 09:44:37PM -0800, Bobby Eshleman wrote:
From: Bobby Eshleman <[email protected]>

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.  Hence, vhost_transport_supports_local_mode() is switched
to return true.

Signed-off-by: Bobby Eshleman <[email protected]>
---
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/[email protected]/
 - Link: 
https://lore.kernel.org/all/[email protected]/
 - Link: 
https://lore.kernel.org/all/[email protected]/
- remove placeholder values (Stefano)
- update comment describe net/net_mode for
 virtio_transport_reset_no_sock()
---
drivers/vhost/vsock.c                   | 47 ++++++++++++++++++------
include/linux/virtio_vsock.h            |  8 +++--
net/vmw_vsock/virtio_transport.c        | 10 ++++--
net/vmw_vsock/virtio_transport_common.c | 63 ++++++++++++++++++++++++---------
net/vmw_vsock/vsock_loopback.c          |  8 +++--
5 files changed, 103 insertions(+), 33 deletions(-)

Reviewed-by: Stefano Garzarella <[email protected]>


diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 4e3856aa2479..e73a6499b9fe 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -46,6 +46,11 @@ 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;
+
+       /* The ns mode at the time vhost_vsock was created */
+       enum vsock_net_mode net_mode;

        /* Link to global vhost_vsock_hash, writes use vhost_vsock_mutex */
        struct hlist_node hash;
@@ -66,13 +71,14 @@ static u32 vhost_transport_get_local_cid(void)

static bool vhost_transport_supports_local_mode(void)
{
-       return false;
+       return true;
}

/* Callers that dereference the return value must hold vhost_vsock_mutex or the
 * RCU read lock.
 */
-static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
+static struct vhost_vsock *vhost_vsock_get(u32 guest_cid, struct net *net,
+                                          enum vsock_net_mode mode)
{
        struct vhost_vsock *vsock;

@@ -83,9 +89,10 @@ 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, mode, vsock->net,
+                                        vsock->net_mode))
                        return vsock;
-
        }

        return NULL;
@@ -274,7 +281,8 @@ 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,
+                        enum vsock_net_mode net_mode)
{
        struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
        struct vhost_vsock *vsock;
@@ -283,7 +291,7 @@ 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, net_mode);
        if (!vsock) {
                rcu_read_unlock();
                kfree_skb(skb);
@@ -310,7 +318,8 @@ 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)), vsk->net_mode);
        if (!vsock)
                goto out;

@@ -470,11 +479,12 @@ 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, vsk->net_mode);

        if (vsock)
                seqpacket_allow = vsock->seqpacket_allow;
@@ -545,7 +555,8 @@ 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, vsock->net_mode);
                else
                        kfree_skb(skb);

@@ -662,6 +673,7 @@ 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
@@ -677,6 +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);
+
        vsock->guest_cid = 0; /* no CID assigned yet */
        vsock->seqpacket_allow = false;

@@ -716,7 +739,8 @@ static void vhost_vsock_reset_orphans(struct sock *sk)
         */

        /* 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),
+                           vsk->net_mode))
                return;

        /* If the close timeout is pending, let it expire.  This avoids races
@@ -761,6 +785,7 @@ 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;
@@ -787,7 +812,7 @@ 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, vsock->net_mode);
        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 0c67543a45c8..5ed6136a4ed4 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -173,6 +173,8 @@ struct virtio_vsock_pkt_info {
        u32 remote_cid, remote_port;
        struct vsock_sock *vsk;
        struct msghdr *msg;
+       struct net *net;
+       enum vsock_net_mode net_mode;
        u32 pkt_len;
        u16 type;
        u16 op;
@@ -185,7 +187,8 @@ 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,
+                       enum vsock_net_mode net_mode);

        /* Used in MSG_ZEROCOPY mode. Checks, that provided data
         * (number of buffers) could be transmitted with zerocopy
@@ -280,7 +283,8 @@ 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,
+                              enum vsock_net_mode net_mode);
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 af4fbce0baab..106d3f25a5cb 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -243,7 +243,8 @@ 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,
+                         enum vsock_net_mode net_mode)
{
        struct virtio_vsock_hdr *hdr;
        struct virtio_vsock *vsock;
@@ -675,7 +676,12 @@ 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, VSOCK_NET_MODE_GLOBAL);
                }
        } while (!virtqueue_enable_cb(vq));

diff --git a/net/vmw_vsock/virtio_transport_common.c 
b/net/vmw_vsock/virtio_transport_common.c
index 675eb9d83549..5bb498caa19e 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, info->net_mode);
                if (ret < 0)
                        break;

@@ -527,6 +527,8 @@ 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)),
+               .net_mode = vsk->net_mode,
        };

        return virtio_transport_send_pkt_info(vsk, &info);
@@ -1067,6 +1069,8 @@ 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)),
+               .net_mode = vsk->net_mode,
        };

        return virtio_transport_send_pkt_info(vsk, &info);
@@ -1082,6 +1086,8 @@ 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)),
+               .net_mode = vsk->net_mode,
        };

        return virtio_transport_send_pkt_info(vsk, &info);
@@ -1108,6 +1114,8 @@ virtio_transport_stream_enqueue(struct vsock_sock *vsk,
                .msg = msg,
                .pkt_len = len,
                .vsk = vsk,
+               .net = sock_net(sk_vsock(vsk)),
+               .net_mode = vsk->net_mode,
        };

        return virtio_transport_send_pkt_info(vsk, &info);
@@ -1145,6 +1153,8 @@ static int virtio_transport_reset(struct vsock_sock *vsk,
                .op = VIRTIO_VSOCK_OP_RST,
                .reply = !!skb,
                .vsk = vsk,
+               .net = sock_net(sk_vsock(vsk)),
+               .net_mode = vsk->net_mode,
        };

        /* Send RST only if the original pkt is not a RST pkt */
@@ -1156,9 +1166,14 @@ 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 and net_mode refer 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,
+                                         enum vsock_net_mode net_mode)
{
        struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
        struct virtio_vsock_pkt_info info = {
@@ -1171,6 +1186,13 @@ 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 or net_mode are not defined here because we pass
+                * net and net_mode directly to t->send_pkt(), instead of
+                * relying on virtio_transport_send_pkt_info() to pass them to
+                * t->send_pkt(). They are not needed by
+                * virtio_transport_alloc_skb().
+                */
        };
        struct sk_buff *reply;

@@ -1189,7 +1211,7 @@ 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, net_mode);
}

/* This function should be called with sk_lock held and SOCK_DONE set */
@@ -1471,6 +1493,8 @@ 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)),
+               .net_mode = vsk->net_mode,
        };

        return virtio_transport_send_pkt_info(vsk, &info);
@@ -1513,12 +1537,14 @@ 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),
+                                              vsk->net_mode);
                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),
+                                              vsk->net_mode);
                return -ENOMEM;
        }

@@ -1526,13 +1552,15 @@ 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),
+                                              vsk->net_mode);
                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),
+                                              vsk->net_mode);
                return -ENOMEM;
        }

@@ -1554,7 +1582,8 @@ 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),
+                                              vsk->net_mode);
                sock_put(child);
                return ret;
        }
@@ -1582,7 +1611,8 @@ 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,
+                              enum vsock_net_mode net_mode)
{
        struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
        struct sockaddr_vm src, dst;
@@ -1605,24 +1635,25 @@ 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, net_mode);
                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, net_mode);
        if (!sk) {
-               sk = vsock_find_bound_socket(&dst);
+               sk = vsock_find_bound_socket_net(&dst, net, net_mode);
                if (!sk) {
-                       (void)virtio_transport_reset_no_sock(t, skb);
+                       (void)virtio_transport_reset_no_sock(t, skb, net,
+                                                            net_mode);
                        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, net_mode);
                sock_put(sk);
                goto free_pkt;
        }
@@ -1641,7 +1672,7 @@ 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, net_mode);
                release_sock(sk);
                sock_put(sk);
                goto free_pkt;
@@ -1673,7 +1704,7 @@ 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, net_mode);
                kfree_skb(skb);
                break;
        }
diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c
index 1e25c1a6b43f..a730fa74d2d9 100644
--- a/net/vmw_vsock/vsock_loopback.c
+++ b/net/vmw_vsock/vsock_loopback.c
@@ -31,7 +31,8 @@ static bool vsock_loopback_supports_local_mode(void)
        return true;
}

-static int vsock_loopback_send_pkt(struct sk_buff *skb)
+static int vsock_loopback_send_pkt(struct sk_buff *skb, struct net *net,
+                                  enum vsock_net_mode net_mode)
{
        struct vsock_loopback *vsock = &the_vsock_loopback;
        int len = skb->len;
@@ -138,7 +139,10 @@ 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),
+                                         vsock_sk(skb->sk)->net_mode);
        }
}


--
2.47.3



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