Re: [PATCH v7 13/17] media: uvcvideo: Return -EACCES to inactive controls

[Ricardo Ribalda <ribalda@chromium.org>]

Hi Hans

Thanks for testing this.




On Fri, Mar 19, 2021 at 10:10 AM Hans Verkuil <hverkuil-cisco@xs4all.nl> wrote:
>
> On 18/03/2021 21:29, Ricardo Ribalda wrote:
> > If a control is inactive return -EACCES to let the userspace know that
> > the value will not be applied automatically when the control is active
> > again.
> >
> > Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> > Suggested-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > ---
> >  drivers/media/usb/uvc/uvc_ctrl.c | 68 ++++++++++++++++++++++----------
> >  drivers/media/usb/uvc/uvc_v4l2.c | 11 +++++-
> >  drivers/media/usb/uvc/uvcvideo.h |  2 +-
> >  3 files changed, 58 insertions(+), 23 deletions(-)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> > index 24fd5afc4e4f..1ec8333811bc 100644
> > --- a/drivers/media/usb/uvc/uvc_ctrl.c
> > +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> > @@ -1046,8 +1046,33 @@ static int uvc_query_v4l2_class(struct uvc_video_chain *chain, u32 req_id,
> >       return 0;
> >  }
> >
> > +static bool uvc_ctrl_is_inactive(struct uvc_video_chain *chain,
> > +                              struct uvc_control *ctrl,
> > +                              struct uvc_control_mapping *mapping)
> > +{
> > +     struct uvc_control_mapping *master_map = NULL;
> > +     struct uvc_control *master_ctrl = NULL;
> > +     s32 val;
> > +     int ret;
> > +
> > +     if (!mapping->master_id)
> > +             return false;
> > +
> > +     __uvc_find_control(ctrl->entity, mapping->master_id, &master_map,
> > +                        &master_ctrl, 0);
> > +
> > +     if (!master_ctrl || !(master_ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR))
> > +             return false;
> > +
> > +     ret = __uvc_ctrl_get(chain, master_ctrl, master_map, &val);
> > +     if (ret < 0 || val == mapping->master_manual)
> > +             return false;
> > +
> > +     return true;
> > +}
>
> This doesn't work. The problem is that you need to test the new value for the
> master control against master_manual, and you are testing against the old value.
>
> So for my uvc camera I have this situation after boot:
>
>                   auto_exposure 0x009a0901 (menu)   : min=0 max=3 default=3 value=3 (Aperture Priority Mode)
>                                 1: Manual Mode
>                                 3: Aperture Priority Mode
>          exposure_time_absolute 0x009a0902 (int)    : min=3 max=2047 step=1 default=250 value=250 flags=inactive
>
> But trying to change both auto_exposure to manual AND set the new exposure_time_absolute
> will fail:
>
> $ v4l2-ctl -c auto_exposure=1,exposure_time_absolute=251
> VIDIOC_S_EXT_CTRLS: failed: Permission denied
> Error setting controls: Permission denied
>
> This works though with the uvc driver as is currently in the kernel.
>
> Unfortunately, this is not something that is explicitly tested in v4l2-compliance.
>

Can you try dropping this patch and relaying on  media: uvcvideo: Set
error_idx during ctrl_commit errors ?

thanks!

> Regards,
>
>         Hans
>
> > +
> >  int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id,
> > -                        bool read)
> > +                        unsigned long ioctl)
> >  {
> >       struct uvc_control_mapping *mapping;
> >       struct uvc_control *ctrl;
> > @@ -1059,11 +1084,26 @@ int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id,
> >       if (!ctrl)
> >               return -EINVAL;
> >
> > -     if (!(ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR) && read)
> > -             return -EACCES;
> > -
> > -     if (!(ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR) && !read)
> > -             return -EACCES;
> > +     switch (ioctl) {
> > +     case VIDIOC_G_CTRL:
> > +     case VIDIOC_G_EXT_CTRLS:
> > +             if (!(ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR))
> > +                     return -EACCES;
> > +             break;
> > +     case VIDIOC_S_EXT_CTRLS:
> > +     case VIDIOC_S_CTRL:
> > +             if (!(ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR))
> > +                     return -EACCES;
> > +             if (uvc_ctrl_is_inactive(chain, ctrl, mapping))
> > +                     return -EACCES;
> > +             break;
> > +     case VIDIOC_TRY_EXT_CTRLS:
> > +             if (!(ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR))
> > +                     return -EACCES;
> > +             break;
> > +     default:
> > +             return -EINVAL;
> > +     }
> >
> >       return 0;
> >  }
> > @@ -1087,8 +1127,6 @@ static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
> >       struct uvc_control_mapping *mapping,
> >       struct v4l2_queryctrl *v4l2_ctrl)
> >  {
> > -     struct uvc_control_mapping *master_map = NULL;
> > -     struct uvc_control *master_ctrl = NULL;
> >       const struct uvc_menu_info *menu;
> >       unsigned int i;
> >
> > @@ -1104,18 +1142,8 @@ static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
> >       if (!(ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR))
> >               v4l2_ctrl->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> >
> > -     if (mapping->master_id)
> > -             __uvc_find_control(ctrl->entity, mapping->master_id,
> > -                                &master_map, &master_ctrl, 0);
> > -     if (master_ctrl && (master_ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR)) {
> > -             s32 val;
> > -             int ret = __uvc_ctrl_get(chain, master_ctrl, master_map, &val);
> > -             if (ret < 0)
> > -                     return ret;
> > -
> > -             if (val != mapping->master_manual)
> > -                             v4l2_ctrl->flags |= V4L2_CTRL_FLAG_INACTIVE;
> > -     }
> > +     if (uvc_ctrl_is_inactive(chain, ctrl, mapping))
> > +             v4l2_ctrl->flags |= V4L2_CTRL_FLAG_INACTIVE;
> >
> >       if (!ctrl->cached) {
> >               int ret = uvc_ctrl_populate_cache(chain, ctrl);
> > diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> > index fbb99f3c2fb4..ddebdeb5a81b 100644
> > --- a/drivers/media/usb/uvc/uvc_v4l2.c
> > +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> > @@ -999,6 +999,10 @@ static int uvc_ioctl_g_ctrl(struct file *file, void *fh,
> >       struct v4l2_ext_control xctrl;
> >       int ret;
> >
> > +     ret = uvc_ctrl_is_accessible(chain, ctrl->id, VIDIOC_G_CTRL);
> > +     if (ret)
> > +             return ret;
> > +
> >       memset(&xctrl, 0, sizeof(xctrl));
> >       xctrl.id = ctrl->id;
> >
> > @@ -1023,6 +1027,10 @@ static int uvc_ioctl_s_ctrl(struct file *file, void *fh,
> >       struct v4l2_ext_control xctrl;
> >       int ret;
> >
> > +     ret = uvc_ctrl_is_accessible(chain, ctrl->id, VIDIOC_S_CTRL);
> > +     if (ret)
> > +             return ret;
> > +
> >       memset(&xctrl, 0, sizeof(xctrl));
> >       xctrl.id = ctrl->id;
> >       xctrl.value = ctrl->value;
> > @@ -1054,8 +1062,7 @@ static int uvc_ctrl_check_access(struct uvc_video_chain *chain,
> >       int ret = 0;
> >
> >       for (i = 0; i < ctrls->count; ++ctrl, ++i) {
> > -             ret = uvc_ctrl_is_accessible(chain, ctrl->id,
> > -                                         ioctl == VIDIOC_G_EXT_CTRLS);
> > +             ret = uvc_ctrl_is_accessible(chain, ctrl->id, ioctl);
> >               if (ret)
> >                       break;
> >       }
> > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> > index 9471c342a310..a93aeedb5499 100644
> > --- a/drivers/media/usb/uvc/uvcvideo.h
> > +++ b/drivers/media/usb/uvc/uvcvideo.h
> > @@ -903,7 +903,7 @@ static inline int uvc_ctrl_rollback(struct uvc_fh *handle)
> >  int uvc_ctrl_get(struct uvc_video_chain *chain, struct v4l2_ext_control *xctrl);
> >  int uvc_ctrl_set(struct uvc_fh *handle, struct v4l2_ext_control *xctrl);
> >  int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id,
> > -                        bool read);
> > +                        unsigned long ioctl);
> >
> >  int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
> >                     struct uvc_xu_control_query *xqry);
> >
>


-- 
Ricardo Ribalda