VSOCK: Handle changes to the VMCI context ID.

The VMCI context ID of a virtual machine may change at any time. There
is a VMCI event which signals this but datagrams may be processed before
this is handled. It is therefore necessary to be flexible about the
destination context ID of any datagrams received. (It can be assumed to
be correct because it is provided by the hypervisor.) The context ID on
existing sockets should be updated to reflect how the hypervisor is
currently referring to the system.

Signed-off-by: Reilly Grant <grantr@vmware.com>
Acked-by: Andy King <acking@vmware.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.c
index a70ace8..1f6508e 100644
--- a/net/vmw_vsock/vmci_transport.c
+++ b/net/vmw_vsock/vmci_transport.c
@@ -464,19 +464,16 @@
 	struct vsock_sock *vlistener;
 	struct vsock_sock *vpending;
 	struct sock *pending;
+	struct sockaddr_vm src;
+
+	vsock_addr_init(&src, pkt->dg.src.context, pkt->src_port);
 
 	vlistener = vsock_sk(listener);
 
 	list_for_each_entry(vpending, &vlistener->pending_links,
 			    pending_links) {
-		struct sockaddr_vm src;
-		struct sockaddr_vm dst;
-
-		vsock_addr_init(&src, pkt->dg.src.context, pkt->src_port);
-		vsock_addr_init(&dst, pkt->dg.dst.context, pkt->dst_port);
-
 		if (vsock_addr_equals_addr(&src, &vpending->remote_addr) &&
-		    vsock_addr_equals_addr(&dst, &vpending->local_addr)) {
+		    pkt->dst_port == vpending->local_addr.svm_port) {
 			pending = sk_vsock(vpending);
 			sock_hold(pending);
 			goto found;
@@ -739,10 +736,15 @@
 	 */
 	bh_lock_sock(sk);
 
-	if (!sock_owned_by_user(sk) && sk->sk_state == SS_CONNECTED)
-		vmci_trans(vsk)->notify_ops->handle_notify_pkt(
-				sk, pkt, true, &dst, &src,
-				&bh_process_pkt);
+	if (!sock_owned_by_user(sk)) {
+		/* The local context ID may be out of date, update it. */
+		vsk->local_addr.svm_cid = dst.svm_cid;
+
+		if (sk->sk_state == SS_CONNECTED)
+			vmci_trans(vsk)->notify_ops->handle_notify_pkt(
+					sk, pkt, true, &dst, &src,
+					&bh_process_pkt);
+	}
 
 	bh_unlock_sock(sk);
 
@@ -902,6 +904,9 @@
 
 	lock_sock(sk);
 
+	/* The local context ID may be out of date. */
+	vsock_sk(sk)->local_addr.svm_cid = pkt->dg.dst.context;
+
 	switch (sk->sk_state) {
 	case SS_LISTEN:
 		vmci_transport_recv_listen(sk, pkt);
@@ -958,6 +963,10 @@
 	pending = vmci_transport_get_pending(sk, pkt);
 	if (pending) {
 		lock_sock(pending);
+
+		/* The local context ID may be out of date. */
+		vsock_sk(pending)->local_addr.svm_cid = pkt->dg.dst.context;
+
 		switch (pending->sk_state) {
 		case SS_CONNECTING:
 			err = vmci_transport_recv_connecting_server(sk,