From 90712c1a495c2aa4b10dd8127fdd7f1a0cd9ef00 Mon Sep 17 00:00:00 2001 From: Jacopo Mondi Date: Tue, 7 Apr 2020 17:21:57 +0200 Subject: [PATCH] media: v4l2-dev: Add v4l2_device_register_ro_subdev_node() Add to the V4L2 core 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. Acked-by: Sakari Ailus Signed-off-by: Jacopo Mondi --- drivers/media/v4l2-core/v4l2-device.c | 7 ++-- drivers/media/v4l2-core/v4l2-subdev.c | 19 ++++++++++ include/media/v4l2-dev.h | 7 ++++ include/media/v4l2-device.h | 50 ++++++++++++++++++++++++--- 4 files changed, 77 insertions(+), 6 deletions(-) --- a/drivers/media/v4l2-core/v4l2-device.c +++ b/drivers/media/v4l2-core/v4l2-device.c @@ -189,7 +189,8 @@ static void v4l2_device_release_subdev_n 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; @@ -218,6 +219,8 @@ int v4l2_device_register_subdev_nodes(st vdev->fops = &v4l2_subdev_fops; vdev->release = v4l2_device_release_subdev_node; vdev->ctrl_handler = sd->ctrl_handler; + if (read_only) + set_bit(V4L2_FL_SUBDEV_RO_DEVNODE, &vdev->flags); err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1, sd->owner); if (err < 0) { @@ -255,7 +258,7 @@ clean_up: return err; } -EXPORT_SYMBOL_GPL(v4l2_device_register_subdev_nodes); +EXPORT_SYMBOL_GPL(__v4l2_device_register_subdev_nodes); void v4l2_device_unregister_subdev(struct v4l2_subdev *sd) { --- 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 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_subdev = test_bit(V4L2_FL_SUBDEV_RO_DEVNODE, &vdev->flags); int rval; #endif @@ -453,6 +454,9 @@ static long subdev_do_ioctl(struct file case VIDIOC_SUBDEV_S_FMT: { struct v4l2_subdev_format *format = arg; + if (format->which != V4L2_SUBDEV_FORMAT_TRY && ro_subdev) + 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 struct v4l2_subdev_crop *crop = arg; struct v4l2_subdev_selection sel; + if (crop->which != V4L2_SUBDEV_FORMAT_TRY && ro_subdev) + 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 case VIDIOC_SUBDEV_S_FRAME_INTERVAL: { struct v4l2_subdev_frame_interval *fi = arg; + if (ro_subdev) + 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 case VIDIOC_SUBDEV_S_SELECTION: { struct v4l2_subdev_selection *sel = arg; + if (sel->which != V4L2_SUBDEV_FORMAT_TRY && ro_subdev) + 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 return v4l2_subdev_call(sd, video, g_dv_timings, arg); case VIDIOC_SUBDEV_S_DV_TIMINGS: + if (ro_subdev) + 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 case VIDIOC_SUBDEV_S_STD: { v4l2_std_id *std = arg; + if (ro_subdev) + return -EPERM; + return v4l2_subdev_call(sd, video, s_std, *std); } --- 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_SUBDEV_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_SUBDEV_RO_DEVNODE = 3, }; /* Priority helper functions */ --- a/include/media/v4l2-device.h +++ b/include/media/v4l2-device.h @@ -174,14 +174,56 @@ int __must_check v4l2_device_register_su void v4l2_device_unregister_subdev(struct v4l2_subdev *sd); /** - * v4l2_device_register_subdev_nodes - Registers device nodes for all subdevs - * of the v4l2 device that are marked with - * the %V4L2_SUBDEV_FL_HAS_DEVNODE flag. + * __v4l2_device_register_ro_subdev_nodes - Registers 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 + * @read_only: subdevices read-only flag. True to register the subdevices + * device nodes in read-only mode, false to allow full access to the + * subdevice userspace API. */ int __must_check -v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev); +__v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev, + bool read_only); + +/** + * v4l2_device_register_subdev_nodes - Registers subdevices device nodes with + * unrestricted access to the subdevice userspace operations + * + * Internally calls __v4l2_device_register_subdev_nodes(). See its documentation + * for more details. + * + * @v4l2_dev: pointer to struct v4l2_device + */ +static inline int __must_check +v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev) +{ +#if defined(CONFIG_VIDEO_V4L2_SUBDEV_API) + return __v4l2_device_register_subdev_nodes(v4l2_dev, false); +#else + return 0; +#endif +} + +/** + * v4l2_device_register_ro_subdev_nodes - Registers subdevices device nodes + * in read-only mode + * + * Internally calls __v4l2_device_register_subdev_nodes(). See its documentation + * for more details. + * + * @v4l2_dev: pointer to struct v4l2_device + */ +static inline int __must_check +v4l2_device_register_ro_subdev_nodes(struct v4l2_device *v4l2_dev) +{ +#if defined(CONFIG_VIDEO_V4L2_SUBDEV_API) + return __v4l2_device_register_subdev_nodes(v4l2_dev, true); +#else + return 0; +#endif +} /** * v4l2_subdev_notify - Sends a notification to v4l2_device.