vsock: add support for SIOCOUTQ ioctl

Add support for ioctl(s) in AF_VSOCK.
The only ioctl available is SIOCOUTQ/TIOCOUTQ, which returns the number
of unsent bytes in the socket. This information is transport-specific
and is delegated to them using a callback.
Suggested-by: Daan De Meyer <daan.j.demeyer@gmail.com>
Signed-off-by: Luigi Leonardi <luigi.leonardi@outlook.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/af_vsock.h

@@ -169,6 +169,9 @@ struct vsock_transport {
 	void (*notify_buffer_size)(struct vsock_sock *, u64 *);
 	int (*notify_set_rcvlowat)(struct vsock_sock *vsk, int val);
 
+	/* SIOCOUTQ ioctl */
+	ssize_t (*unsent_bytes)(struct vsock_sock *vsk);
+
 	/* Shutdown. */
 	int (*shutdown)(struct vsock_sock *, int);
 

net/vmw_vsock/af_vsock.c

@@ -112,6 +112,7 @@
 #include <net/sock.h>
 #include <net/af_vsock.h>
 #include <uapi/linux/vm_sockets.h>
+#include <uapi/asm-generic/ioctls.h>
 
 static int __vsock_bind(struct sock *sk, struct sockaddr_vm *addr);
 static void vsock_sk_destruct(struct sock *sk);
@@ -1292,6 +1293,57 @@ int vsock_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
 }
 EXPORT_SYMBOL_GPL(vsock_dgram_recvmsg);
 
+static int vsock_do_ioctl(struct socket *sock, unsigned int cmd,
+			  int __user *arg)
+{
+	struct sock *sk = sock->sk;
+	struct vsock_sock *vsk;
+	int ret;
+
+	vsk = vsock_sk(sk);
+
+	switch (cmd) {
+	case SIOCOUTQ: {
+		ssize_t n_bytes;
+
+		if (!vsk->transport || !vsk->transport->unsent_bytes) {
+			ret = -EOPNOTSUPP;
+			break;
+		}
+
+		if (sock_type_connectible(sk->sk_type) && sk->sk_state == TCP_LISTEN) {
+			ret = -EINVAL;
+			break;
+		}
+
+		n_bytes = vsk->transport->unsent_bytes(vsk);
+		if (n_bytes < 0) {
+			ret = n_bytes;
+			break;
+		}
+
+		ret = put_user(n_bytes, arg);
+		break;
+	}
+	default:
+		ret = -ENOIOCTLCMD;
+	}
+
+	return ret;
+}
+
+static int vsock_ioctl(struct socket *sock, unsigned int cmd,
+		       unsigned long arg)
+{
+	int ret;
+
+	lock_sock(sock->sk);
+	ret = vsock_do_ioctl(sock, cmd, (int __user *)arg);
+	release_sock(sock->sk);
+
+	return ret;
+}
+
 static const struct proto_ops vsock_dgram_ops = {
 	.family = PF_VSOCK,
 	.owner = THIS_MODULE,
@@ -1302,7 +1354,7 @@ static const struct proto_ops vsock_dgram_ops = {
 	.accept = sock_no_accept,
 	.getname = vsock_getname,
 	.poll = vsock_poll,
-	.ioctl = sock_no_ioctl,
+	.ioctl = vsock_ioctl,
 	.listen = sock_no_listen,
 	.shutdown = vsock_shutdown,
 	.sendmsg = vsock_dgram_sendmsg,
@@ -2286,7 +2338,7 @@ static const struct proto_ops vsock_stream_ops = {
 	.accept = vsock_accept,
 	.getname = vsock_getname,
 	.poll = vsock_poll,
-	.ioctl = sock_no_ioctl,
+	.ioctl = vsock_ioctl,
 	.listen = vsock_listen,
 	.shutdown = vsock_shutdown,
 	.setsockopt = vsock_connectible_setsockopt,
@@ -2308,7 +2360,7 @@ static const struct proto_ops vsock_seqpacket_ops = {
 	.accept = vsock_accept,
 	.getname = vsock_getname,
 	.poll = vsock_poll,
-	.ioctl = sock_no_ioctl,
+	.ioctl = vsock_ioctl,
 	.listen = vsock_listen,
 	.shutdown = vsock_shutdown,
 	.setsockopt = vsock_connectible_setsockopt,