media: subdev: disallow ioctl for saa6588/davinci

The saa6588_ioctl() function expects to get called from other kernel
functions with a 'saa6588_command' pointer, but I found nothing stops it
from getting called from user space instead, which seems rather dangerous.

The same thing happens in the davinci vpbe driver with its VENC_GET_FLD
command.

As a quick fix, add a separate .command() callback pointer for this
driver and change the two callers over to that.  This change can easily
get backported to stable kernels if necessary, but since there are only
two drivers, we may want to eventually replace this with a set of more
specialized callbacks in the long run.

Fixes: c3fda7f8 ("V4L/DVB (10537): saa6588: convert to v4l2_subdev.")
Cc: stable@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/i2c/saa6588.c

@@ -380,7 +380,7 @@ static void saa6588_configure(struct saa6588 *s)
 
 /* ---------------------------------------------------------------------- */
 
-static long saa6588_ioctl(struct v4l2_subdev *sd, unsigned int cmd, void *arg)
+static long saa6588_command(struct v4l2_subdev *sd, unsigned int cmd, void *arg)
 {
 	struct saa6588 *s = to_saa6588(sd);
 	struct saa6588_command *a = arg;
@@ -433,7 +433,7 @@ static int saa6588_s_tuner(struct v4l2_subdev *sd, const struct v4l2_tuner *vt)
 /* ----------------------------------------------------------------------- */
 
 static const struct v4l2_subdev_core_ops saa6588_core_ops = {
-	.ioctl = saa6588_ioctl,
+	.command = saa6588_command,
 };
 
 static const struct v4l2_subdev_tuner_ops saa6588_tuner_ops = {

drivers/media/pci/bt8xx/bttv-driver.c

@@ -3179,7 +3179,7 @@ static int radio_release(struct file *file)
 
 	btv->radio_user--;
 
-	bttv_call_all(btv, core, ioctl, SAA6588_CMD_CLOSE, &cmd);
+	bttv_call_all(btv, core, command, SAA6588_CMD_CLOSE, &cmd);
 
 	if (btv->radio_user == 0)
 		btv->has_radio_tuner = 0;
@@ -3260,7 +3260,7 @@ static ssize_t radio_read(struct file *file, char __user *data,
 	cmd.result = -ENODEV;
 	radio_enable(btv);
 
-	bttv_call_all(btv, core, ioctl, SAA6588_CMD_READ, &cmd);
+	bttv_call_all(btv, core, command, SAA6588_CMD_READ, &cmd);
 
 	return cmd.result;
 }
@@ -3281,7 +3281,7 @@ static __poll_t radio_poll(struct file *file, poll_table *wait)
 	cmd.instance = file;
 	cmd.event_list = wait;
 	cmd.poll_mask = res;
-	bttv_call_all(btv, core, ioctl, SAA6588_CMD_POLL, &cmd);
+	bttv_call_all(btv, core, command, SAA6588_CMD_POLL, &cmd);
 
 	return cmd.poll_mask;
 }

drivers/media/pci/saa7134/saa7134-video.c

@@ -1181,7 +1181,7 @@ static int video_release(struct file *file)
 
 	saa_call_all(dev, tuner, standby);
 	if (vdev->vfl_type == VFL_TYPE_RADIO)
-		saa_call_all(dev, core, ioctl, SAA6588_CMD_CLOSE, &cmd);
+		saa_call_all(dev, core, command, SAA6588_CMD_CLOSE, &cmd);
 	mutex_unlock(&dev->lock);
 
 	return 0;
@@ -1200,7 +1200,7 @@ static ssize_t radio_read(struct file *file, char __user *data,
 	cmd.result = -ENODEV;
 
 	mutex_lock(&dev->lock);
-	saa_call_all(dev, core, ioctl, SAA6588_CMD_READ, &cmd);
+	saa_call_all(dev, core, command, SAA6588_CMD_READ, &cmd);
 	mutex_unlock(&dev->lock);
 
 	return cmd.result;
@@ -1216,7 +1216,7 @@ static __poll_t radio_poll(struct file *file, poll_table *wait)
 	cmd.event_list = wait;
 	cmd.poll_mask = 0;
 	mutex_lock(&dev->lock);
-	saa_call_all(dev, core, ioctl, SAA6588_CMD_POLL, &cmd);
+	saa_call_all(dev, core, command, SAA6588_CMD_POLL, &cmd);
 	mutex_unlock(&dev->lock);
 
 	return rc | cmd.poll_mask;

drivers/media/platform/davinci/vpbe_display.c

@@ -47,7 +47,7 @@ static int venc_is_second_field(struct vpbe_display *disp_dev)
 
 	ret = v4l2_subdev_call(vpbe_dev->venc,
 			       core,
-			       ioctl,
+			       command,
 			       VENC_GET_FLD,
 			       &val);
 	if (ret < 0) {

drivers/media/platform/davinci/vpbe_venc.c

@@ -521,9 +521,7 @@ static int venc_s_routing(struct v4l2_subdev *sd, u32 input, u32 output,
 	return ret;
 }
 
-static long venc_ioctl(struct v4l2_subdev *sd,
-			unsigned int cmd,
-			void *arg)
+static long venc_command(struct v4l2_subdev *sd, unsigned int cmd, void *arg)
 {
 	u32 val;
 
@@ -542,7 +540,7 @@ static long venc_ioctl(struct v4l2_subdev *sd,
 }
 
 static const struct v4l2_subdev_core_ops venc_core_ops = {
-	.ioctl      = venc_ioctl,
+	.command      = venc_command,
 };
 
 static const struct v4l2_subdev_video_ops venc_video_ops = {

include/media/v4l2-subdev.h

@@ -162,6 +162,9 @@ struct v4l2_subdev_io_pin_config {
  * @s_gpio: set GPIO pins. Very simple right now, might need to be extended with
  *	a direction argument if needed.
  *
+ * @command: called by in-kernel drivers in order to call functions internal
+ *	   to subdev drivers driver that have a separate callback.
+ *
  * @ioctl: called at the end of ioctl() syscall handler at the V4L2 core.
  *	   used to provide support for private ioctls used on the driver.
  *
@@ -193,6 +196,7 @@ struct v4l2_subdev_core_ops {
 	int (*load_fw)(struct v4l2_subdev *sd);
 	int (*reset)(struct v4l2_subdev *sd, u32 val);
 	int (*s_gpio)(struct v4l2_subdev *sd, u32 val);
+	long (*command)(struct v4l2_subdev *sd, unsigned int cmd, void *arg);
 	long (*ioctl)(struct v4l2_subdev *sd, unsigned int cmd, void *arg);
 #ifdef CONFIG_COMPAT
 	long (*compat_ioctl32)(struct v4l2_subdev *sd, unsigned int cmd,