VSOCK: Send reset control packet when socket is partially bound

If a server side socket is bound to an address, but not in the listening
state yet, incoming connection requests should receive a reset control
packet in response. However, the function used to send the reset
silently drops the reset packet if the sending socket isn't bound
to a remote address (as is the case for a bound socket not yet in
the listening state). This change fixes this by using the src
of the incoming packet as destination for the reset packet in
this case.

Fixes: d021c344 ("VSOCK: Introduce VM Sockets")
Reviewed-by: Adit Ranadive <aditr@vmware.com>
Reviewed-by: Vishnu Dasa <vdasa@vmware.com>
Signed-off-by: Jorgen Hansen <jhansen@vmware.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/vmw_vsock/vmci_transport.c

@@ -264,7 +264,8 @@ vmci_transport_send_control_pkt_bh(struct sockaddr_vm *src,
 }
 
 static int
-vmci_transport_send_control_pkt(struct sock *sk,
+vmci_transport_alloc_send_control_pkt(struct sockaddr_vm *src,
+				      struct sockaddr_vm *dst,
 				      enum vmci_transport_packet_type type,
 				      u64 size,
 				      u64 mode,
@@ -273,23 +274,13 @@ vmci_transport_send_control_pkt(struct sock *sk,
 				      struct vmci_handle handle)
 {
 	struct vmci_transport_packet *pkt;
-	struct vsock_sock *vsk;
 	int err;
 
-	vsk = vsock_sk(sk);
-
-	if (!vsock_addr_bound(&vsk->local_addr))
-		return -EINVAL;
-
-	if (!vsock_addr_bound(&vsk->remote_addr))
-		return -EINVAL;
-
 	pkt = kmalloc(sizeof(*pkt), GFP_KERNEL);
 	if (!pkt)
 		return -ENOMEM;
 
-	err = __vmci_transport_send_control_pkt(pkt, &vsk->local_addr,
-						&vsk->remote_addr, type, size,
+	err = __vmci_transport_send_control_pkt(pkt, src, dst, type, size,
 						mode, wait, proto, handle,
 						true);
 	kfree(pkt);
@@ -297,6 +288,31 @@ vmci_transport_send_control_pkt(struct sock *sk,
 	return err;
 }
 
+static int
+vmci_transport_send_control_pkt(struct sock *sk,
+				enum vmci_transport_packet_type type,
+				u64 size,
+				u64 mode,
+				struct vmci_transport_waiting_info *wait,
+				u16 proto,
+				struct vmci_handle handle)
+{
+	struct vsock_sock *vsk;
+
+	vsk = vsock_sk(sk);
+
+	if (!vsock_addr_bound(&vsk->local_addr))
+		return -EINVAL;
+
+	if (!vsock_addr_bound(&vsk->remote_addr))
+		return -EINVAL;
+
+	return vmci_transport_alloc_send_control_pkt(&vsk->local_addr,
+						     &vsk->remote_addr,
+						     type, size, mode,
+						     wait, proto, handle);
+}
+
 static int vmci_transport_send_reset_bh(struct sockaddr_vm *dst,
 					struct sockaddr_vm *src,
 					struct vmci_transport_packet *pkt)
@@ -312,9 +328,26 @@ static int vmci_transport_send_reset_bh(struct sockaddr_vm *dst,
 static int vmci_transport_send_reset(struct sock *sk,
 				     struct vmci_transport_packet *pkt)
 {
+	struct sockaddr_vm *dst_ptr;
+	struct sockaddr_vm dst;
+	struct vsock_sock *vsk;
+
 	if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_RST)
 		return 0;
-	return vmci_transport_send_control_pkt(sk,
+
+	vsk = vsock_sk(sk);
+
+	if (!vsock_addr_bound(&vsk->local_addr))
+		return -EINVAL;
+
+	if (vsock_addr_bound(&vsk->remote_addr)) {
+		dst_ptr = &vsk->remote_addr;
+	} else {
+		vsock_addr_init(&dst, pkt->dg.src.context,
+				pkt->src_port);
+		dst_ptr = &dst;
+	}
+	return vmci_transport_alloc_send_control_pkt(&vsk->local_addr, dst_ptr,
 					     VMCI_TRANSPORT_PACKET_TYPE_RST,
 					     0, 0, NULL, VSOCK_PROTO_INVALID,
 					     VMCI_INVALID_HANDLE);