[PATCH net-next v8 05/14] vsock/loopback: add netns support

[Bobby Eshleman <bobbyeshleman@gmail.com>]

From: Bobby Eshleman <bobbyeshleman@meta.com>

Add NS support to vsock loopback. Sockets in a global mode netns
communicate with each other, regardless of namespace. Sockets in a local
mode netns may only communicate with other sockets within the same
namespace.

Use pernet_ops to install a vsock_loopback for every namespace that is
created (to be used if local mode is enabled).

Retroactively call init/exit on every namespace when the vsock_loopback
module is loaded in order to initialize the per-ns device.

Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
---
Changes in v7:
- drop for_each_net() init/exit, drop net_rwsem, the pernet registration
  handles this automatically and race-free
- flush workqueue before destruction, purge pkt list
- remember net_mode instead of current net mode
- keep space after INIT_WORK()
- change vsock_loopback in netns_vsock to ->priv void ptr
- rename `orig_net_mode` to `net_mode`
- remove useless comment
- protect `register_pernet_subsys()` with `net_rwsem`
- do cleanup before releasing `net_rwsem` when failure happens
- call `unregister_pernet_subsys()` in `vsock_loopback_exit()`
- call `vsock_loopback_deinit_vsock()` in `vsock_loopback_exit()`

Changes in v6:
- init pernet ops for vsock_loopback module
- vsock_loopback: add space in struct to clarify lock protection
- do proper cleanup/unregister on vsock_loopback_exit()
- vsock_loopback: use virtio_vsock_skb_net()

Changes in v5:
- add callbacks code to avoid reverse dependency
- add logic for handling vsock_loopback setup for already existing
  namespaces
---
 include/net/netns/vsock.h      |  2 +
 net/vmw_vsock/vsock_loopback.c | 85 ++++++++++++++++++++++++++++++++++++------
 2 files changed, 75 insertions(+), 12 deletions(-)

diff --git a/include/net/netns/vsock.h b/include/net/netns/vsock.h
index c9a438ad52f2..9d0d8e2fbc37 100644
--- a/include/net/netns/vsock.h
+++ b/include/net/netns/vsock.h
@@ -16,5 +16,7 @@ struct netns_vsock {
 	/* protected by lock */
 	enum vsock_net_mode mode;
 	bool mode_locked;
+
+	void *priv;
 };
 #endif /* __NET_NET_NAMESPACE_VSOCK_H */
diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c
index a8f218f0c5a3..474083d4cfcb 100644
--- a/net/vmw_vsock/vsock_loopback.c
+++ b/net/vmw_vsock/vsock_loopback.c
@@ -28,8 +28,16 @@ static u32 vsock_loopback_get_local_cid(void)
 
 static int vsock_loopback_send_pkt(struct sk_buff *skb)
 {
-	struct vsock_loopback *vsock = &the_vsock_loopback;
+	struct vsock_loopback *vsock;
 	int len = skb->len;
+	struct net *net;
+
+	net = virtio_vsock_skb_net(skb);
+
+	if (virtio_vsock_skb_net_mode(skb) == VSOCK_NET_MODE_LOCAL)
+		vsock = (struct vsock_loopback *)net->vsock.priv;
+	else
+		vsock = &the_vsock_loopback;
 
 	virtio_vsock_skb_queue_tail(&vsock->pkt_queue, skb);
 	queue_work(vsock->workqueue, &vsock->pkt_work);
@@ -134,11 +142,8 @@ static void vsock_loopback_work(struct work_struct *work)
 	}
 }
 
-static int __init vsock_loopback_init(void)
+static int vsock_loopback_init_vsock(struct vsock_loopback *vsock)
 {
-	struct vsock_loopback *vsock = &the_vsock_loopback;
-	int ret;
-
 	vsock->workqueue = alloc_workqueue("vsock-loopback", WQ_PERCPU, 0);
 	if (!vsock->workqueue)
 		return -ENOMEM;
@@ -146,15 +151,73 @@ static int __init vsock_loopback_init(void)
 	skb_queue_head_init(&vsock->pkt_queue);
 	INIT_WORK(&vsock->pkt_work, vsock_loopback_work);
 
+	return 0;
+}
+
+static void vsock_loopback_deinit_vsock(struct vsock_loopback *vsock)
+{
+	if (vsock->workqueue) {
+		flush_work(&vsock->pkt_work);
+		virtio_vsock_skb_queue_purge(&vsock->pkt_queue);
+		destroy_workqueue(vsock->workqueue);
+		vsock->workqueue = NULL;
+	}
+}
+
+static int vsock_loopback_init_net(struct net *net)
+{
+	int ret;
+
+	net->vsock.priv = kzalloc(sizeof(struct vsock_loopback), GFP_KERNEL);
+	if (!net->vsock.priv)
+		return -ENOMEM;
+
+	ret = vsock_loopback_init_vsock((struct vsock_loopback *)net->vsock.priv);
+	if (ret < 0) {
+		kfree(net->vsock.priv);
+		net->vsock.priv = NULL;
+		return ret;
+	}
+
+	return 0;
+}
+
+static void vsock_loopback_exit_net(struct net *net)
+{
+	vsock_loopback_deinit_vsock(net->vsock.priv);
+	kfree(net->vsock.priv);
+	net->vsock.priv = NULL;
+}
+
+static struct pernet_operations vsock_loopback_net_ops = {
+	.init = vsock_loopback_init_net,
+	.exit = vsock_loopback_exit_net,
+};
+
+static int __init vsock_loopback_init(void)
+{
+	struct vsock_loopback *vsock = &the_vsock_loopback;
+	int ret;
+
+	ret = vsock_loopback_init_vsock(vsock);
+	if (ret < 0)
+		return ret;
+
+	ret = register_pernet_subsys(&vsock_loopback_net_ops);
+	if (ret < 0)
+		goto out_deinit_vsock;
+
 	ret = vsock_core_register(&loopback_transport.transport,
 				  VSOCK_TRANSPORT_F_LOCAL);
 	if (ret)
-		goto out_wq;
+		goto out_unregister_pernet_subsys;
 
 	return 0;
 
-out_wq:
-	destroy_workqueue(vsock->workqueue);
+out_unregister_pernet_subsys:
+	unregister_pernet_subsys(&vsock_loopback_net_ops);
+out_deinit_vsock:
+	vsock_loopback_deinit_vsock(vsock);
 	return ret;
 }
 
@@ -164,11 +227,9 @@ static void __exit vsock_loopback_exit(void)
 
 	vsock_core_unregister(&loopback_transport.transport);
 
-	flush_work(&vsock->pkt_work);
-
-	virtio_vsock_skb_queue_purge(&vsock->pkt_queue);
+	unregister_pernet_subsys(&vsock_loopback_net_ops);
 
-	destroy_workqueue(vsock->workqueue);
+	vsock_loopback_deinit_vsock(vsock);
 }
 
 module_init(vsock_loopback_init);

-- 
2.47.3