On 21 June 2016 at 07:39, Michel Dänzer <mic...@daenzer.net> wrote: > On 21.06.2016 15:24, Axel Davy wrote: >> On 21/06/2016 01:26, Michel Dänzer wrote: >>> On 20.06.2016 20:06, Frank Binns wrote: >>>> On 20/06/16 10:48, Michel Dänzer wrote: >>>>> On 18.06.2016 02:41, Frank Binns wrote: >>>>>> Up until now, DRI3 was only used for devices that have render nodes, >>>>>> unless >>>>>> overridden via an environment variable, with it falling back to DRI2 >>>>>> otherwise. >>>>>> This limitation was there in order to support WL_bind_wayland_display >>>>>> as it >>>>>> requires client opened device node fds to be authenticated, which >>>>>> isn't possible >>>>>> when using DRI3. This is an unfortunate compromise as DRI3 provides >>>>>> security >>>>>> benefits over DRI2. >>>>> What exactly is it that works with render nodes but not with >>>>> unauthenticated non-render nodes? Isn't that a kernel bug? >>>> The problem isn't that something doesn't work with unauthenticated >>>> non-render nodes (wouldn't that be the kernel bug?) but that if a >>>> client opens the primary/legacy node it needs the resulting fd to >>>> be authenticated, which isn't supported by the X11 DRI3 protocol. >>> Authentication is required for using certain ioctls of non-render nodes. >>> It sounds like some ioctls are allowed to be used with render nodes but >>> not with unauthenticated non-render nodes, which seems like a kernel bug >>> — why would an ioctl be safe to use without authentication via a render >>> node but not via a non-render node? >>> >>> So, which ioctls required by WL_bind_wayland_display don't work with an >>> unauthenticated non-render node? >>> >>> >> The ioctl to authenticate is possible only when you have the master node >> (owned by the DDX when using X, or by the wayland compositor when using >> Wayland). There is only one master node. >> >> >> On of the motives of render-nodes is precisely to fix these limitations. > > I understand all of that, but it doesn't answer my question. :) > > Since WL_bind_wayland_display works with a render node, it means that > all ioctls it needs work without authentication when using a render > node. The question is, why do the same ioctls require authentication > when using a non-render node? > > I believe the following thread [1] is relevant here.
-Emil [1] https://lists.freedesktop.org/archives/dri-devel/2016-June/110845.html _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev