Add to the V4L2 code a function to register device nodes for video
subdevices in read-only mode.
Registering a device node in read-only mode is useful to expose to
userspace the current sub-device configuration, without allowing
application to change it by using the V4L2 subdevice ioctls.
Signed-off-by: Jacopo Mondi <jacopo@xxxxxxxxxx>
---
drivers/media/v4l2-core/v4l2-device.c | 16 +++++++++++++++-
drivers/media/v4l2-core/v4l2-subdev.c | 19 +++++++++++++++++++
include/media/v4l2-dev.h | 7 +++++++
include/media/v4l2-device.h | 10 ++++++++++
4 files changed, 51 insertions(+), 1 deletion(-)
diff --git a/drivers/media/v4l2-core/v4l2-device.c b/drivers/media/v4l2-core/v4l2-device.c
index 63d6b147b21e..6f9dba36eda1 100644
--- a/drivers/media/v4l2-core/v4l2-device.c
+++ b/drivers/media/v4l2-core/v4l2-device.c
@@ -188,7 +188,8 @@ static void v4l2_device_release_subdev_node(struct video_device *vdev)
kfree(vdev);
}
-int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
+int __v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev,
+ bool read_only)
{
struct video_device *vdev;
struct v4l2_subdev *sd;
@@ -217,6 +218,8 @@ int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
vdev->fops = &v4l2_subdev_fops;
vdev->release = v4l2_device_release_subdev_node;
vdev->ctrl_handler = sd->ctrl_handler;
+ if (read_only)
+ vdev->flags |= V4L2_FL_RO_DEVNODE;
err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
sd->owner);
if (err < 0) {
@@ -254,8 +257,19 @@ int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
return err;
}
+
+int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
+{
+ return __v4l2_device_register_subdev_nodes(v4l2_dev, false);
+}
EXPORT_SYMBOL_GPL(v4l2_device_register_subdev_nodes);
+int v4l2_device_register_ro_subdev_nodes(struct v4l2_device *v4l2_dev)
+{
+ return __v4l2_device_register_subdev_nodes(v4l2_dev, true);
+}
+EXPORT_SYMBOL_GPL(v4l2_device_register_ro_subdev_nodes);
+
void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
{
struct v4l2_device *v4l2_dev;
diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index f725cd9b66b9..9247ee6c293f 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -331,6 +331,7 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg)
struct v4l2_fh *vfh = file->private_data;
#if defined(CONFIG_VIDEO_V4L2_SUBDEV_API)
struct v4l2_subdev_fh *subdev_fh = to_v4l2_subdev_fh(vfh);
+ bool ro_devnode = !!(vdev->flags & V4L2_FL_RO_DEVNODE);
int rval;
#endif
@@ -453,6 +454,9 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg)
case VIDIOC_SUBDEV_S_FMT: {
struct v4l2_subdev_format *format = arg;
+ if (format->which != V4L2_SUBDEV_FORMAT_TRY && ro_devnode)
+ return -EPERM;
+
memset(format->reserved, 0, sizeof(format->reserved));
memset(format->format.reserved, 0, sizeof(format->format.reserved));
return v4l2_subdev_call(sd, pad, set_fmt, subdev_fh->pad, format);
@@ -480,6 +484,9 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg)
struct v4l2_subdev_crop *crop = arg;
struct v4l2_subdev_selection sel;
+ if (crop->which != V4L2_SUBDEV_FORMAT_TRY && ro_devnode)
+ return -EPERM;
+
memset(crop->reserved, 0, sizeof(crop->reserved));
memset(&sel, 0, sizeof(sel));
sel.which = crop->which;
@@ -521,6 +528,9 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg)
case VIDIOC_SUBDEV_S_FRAME_INTERVAL: {
struct v4l2_subdev_frame_interval *fi = arg;
+ if (ro_devnode)
+ return -EPERM;
+
memset(fi->reserved, 0, sizeof(fi->reserved));
return v4l2_subdev_call(sd, video, s_frame_interval, arg);
}
@@ -544,6 +554,9 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg)
case VIDIOC_SUBDEV_S_SELECTION: {
struct v4l2_subdev_selection *sel = arg;
+ if (sel->which != V4L2_SUBDEV_FORMAT_TRY && ro_devnode)
+ return -EPERM;
+
memset(sel->reserved, 0, sizeof(sel->reserved));
return v4l2_subdev_call(
sd, pad, set_selection, subdev_fh->pad, sel);
@@ -580,6 +593,9 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg)
return v4l2_subdev_call(sd, video, g_dv_timings, arg);
case VIDIOC_SUBDEV_S_DV_TIMINGS:
+ if (ro_devnode)
+ return -EPERM;
+
return v4l2_subdev_call(sd, video, s_dv_timings, arg);
case VIDIOC_SUBDEV_G_STD:
@@ -588,6 +604,9 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg)
case VIDIOC_SUBDEV_S_STD: {
v4l2_std_id *std = arg;
+ if (ro_devnode)
+ return -EPERM;
+
return v4l2_subdev_call(sd, video, s_std, *std);
}
diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
index 48531e57cc5a..029873a338f2 100644
--- a/include/media/v4l2-dev.h
+++ b/include/media/v4l2-dev.h
@@ -82,11 +82,18 @@ struct v4l2_ctrl_handler;
* but the old crop API will still work as expected in order to preserve
* backwards compatibility.
* Never set this flag for new drivers.
+ * @V4L2_FL_RO_DEVNODE:
+ * indicates that the video device node is registered in read-only mode.
+ * The flag only applies to device nodes registered for sub-devices, it is
+ * set by the core when the sub-devices device nodes are registered with
+ * v4l2_device_register_ro_subdev_nodes() and used by the sub-device ioctl
+ * handler to restrict access to some ioctl calls.
*/
enum v4l2_video_device_flags {
V4L2_FL_REGISTERED = 0,
V4L2_FL_USES_V4L2_FH = 1,
V4L2_FL_QUIRK_INVERTED_CROP = 2,
+ V4L2_FL_RO_DEVNODE = 3,
};
/* Priority helper functions */
diff --git a/include/media/v4l2-device.h b/include/media/v4l2-device.h
index e0b8f2602670..0df667ba9938 100644
--- a/include/media/v4l2-device.h
+++ b/include/media/v4l2-device.h
@@ -183,6 +183,16 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev *sd);
int __must_check
v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev);
+/**
+ * v4l2_device_register_ro_subdev_nodes - Registers read-only device nodes for
+ * all subdevs of the v4l2 device that are marked with the
+ * %V4L2_SUBDEV_FL_HAS_DEVNODE flag.
+ *
+ * @v4l2_dev: pointer to struct v4l2_device
+ */
+int __must_check
+v4l2_device_register_ro_subdev_nodes(struct v4l2_device *v4l2_dev);
+
/**
* v4l2_subdev_notify - Sends a notification to v4l2_device.
*
--
2.25.1
