On 2019/05/27, Christian König wrote: > Am 27.05.19 um 10:17 schrieb Emil Velikov: > > From: Emil Velikov <emil.velikov@xxxxxxxxxxxxx> > > > > There are cases (in mesa and applications) where one would open the > > primary node without properly authenticating the client. > > > > Sometimes we don't check if the authentication succeeds, but there's > > also cases we simply forget to do it. > > > > The former was a case for Mesa where it did not not check the return > > value of drmGetMagic() [1]. That was fixed recently although, there's > > the question of older drivers or other apps that exbibit this behaviour. > > > > While omitting the call results in issues as seen in [2] and [3]. > > > > In the libva case, libva itself doesn't authenticate the DRM client and > > the vaGetDisplayDRM documentation doesn't mention if the app should > > either. > > > > As of today, the official vainfo utility doesn't authenticate. > > > > To workaround issues like these, some users resort to running their apps > > under sudo. Which admittedly isn't always a good idea. > > > > Since any DRIVER_RENDER driver has sufficient isolation between clients, > > we can use that, for unauthenticated [primary node] ioctls that require > > DRM_AUTH. But only if the respective ioctl is tagged as DRM_RENDER_ALLOW. > > > > v2: > > - Rework/simplify if check (Daniel V) > > - Add examples to commit messages, elaborate. (Daniel V) > > > > v3: > > - Use single unlikely (Daniel V) > > > > v4: > > - Patch was reverted because it broke AMDGPU, apply again. The AMDGPU > > issue is fixed with earlier patch. > > As far as I can see this only affects the following two IOCTLs after > removing DRM_AUTH from the DRM_RENDER_ALLOW IOCTLs: > > DRM_IOCTL_DEF(DRM_IOCTL_PRIME_HANDLE_TO_FD, > > drm_prime_handle_to_fd_ioctl, DRM_AUTH|DRM_UNLOCKED|DRM_RENDER_ALLOW), > > DRM_IOCTL_DEF(DRM_IOCTL_PRIME_FD_TO_HANDLE, > > drm_prime_fd_to_handle_ioctl, DRM_AUTH|DRM_UNLOCKED|DRM_RENDER_ALLOW) > > So I think it would be simpler to just remove DRM_AUTH from those two > instead of allowing it for everybody. > If I understand you correctly this will remove DRM_AUTH also for drivers which expose only a primary node. I'm not sure if that is a good idea. That said, if others are OK with the idea I will prepare a patch. Thanks Emil _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
