af_unix: add compat_ioctl support

The af_unix protocol family has a custom ioctl command (inexplicibly
based on SIOCPROTOPRIVATE), but never had a compat_ioctl handler for
32-bit applications.

Since all commands are compatible here, add a trivial wrapper that
performs the compat_ptr() conversion for SIOCOUTQ/SIOCINQ.  SIOCUNIXFILE
does not use the argument, but it doesn't hurt to also use compat_ptr()
here.

Fixes: ba94f308 ("unix: add ioctl to open a unix socket file with O_PATH")
Cc: netdev@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

net/unix/af_unix.c

@@ -646,6 +646,9 @@ static __poll_t unix_poll(struct file *, struct socket *, poll_table *);
 static __poll_t unix_dgram_poll(struct file *, struct socket *,
 				    poll_table *);
 static int unix_ioctl(struct socket *, unsigned int, unsigned long);
+#ifdef CONFIG_COMPAT
+static int unix_compat_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg);
+#endif
 static int unix_shutdown(struct socket *, int);
 static int unix_stream_sendmsg(struct socket *, struct msghdr *, size_t);
 static int unix_stream_recvmsg(struct socket *, struct msghdr *, size_t, int);
@@ -687,6 +690,9 @@ static const struct proto_ops unix_stream_ops = {
 	.getname =	unix_getname,
 	.poll =		unix_poll,
 	.ioctl =	unix_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl =	unix_compat_ioctl,
+#endif
 	.listen =	unix_listen,
 	.shutdown =	unix_shutdown,
 	.setsockopt =	sock_no_setsockopt,
@@ -710,6 +716,9 @@ static const struct proto_ops unix_dgram_ops = {
 	.getname =	unix_getname,
 	.poll =		unix_dgram_poll,
 	.ioctl =	unix_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl =	unix_compat_ioctl,
+#endif
 	.listen =	sock_no_listen,
 	.shutdown =	unix_shutdown,
 	.setsockopt =	sock_no_setsockopt,
@@ -732,6 +741,9 @@ static const struct proto_ops unix_seqpacket_ops = {
 	.getname =	unix_getname,
 	.poll =		unix_dgram_poll,
 	.ioctl =	unix_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl =	unix_compat_ioctl,
+#endif
 	.listen =	unix_listen,
 	.shutdown =	unix_shutdown,
 	.setsockopt =	sock_no_setsockopt,
@@ -2582,6 +2594,13 @@ static int unix_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 	return err;
 }
 
+#ifdef CONFIG_COMPAT
+static int unix_compat_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
+{
+	return unix_ioctl(sock, cmd, (unsigned long)compat_ptr(arg));
+}
+#endif
+
 static __poll_t unix_poll(struct file *file, struct socket *sock, poll_table *wait)
 {
 	struct sock *sk = sock->sk;