On 2019/05/27, Daniel Vetter wrote: > On Mon, May 27, 2019 at 09:17:29AM +0100, Emil Velikov wrote: > > From: Emil Velikov <emil.velikov@xxxxxxxxxxxxx> > > > > Currently one can circumvent DRM_AUTH, when the ioctl is exposed via the > > render node. A seemingly deliberate design decision. > > > > Hence we can drop the DRM_AUTH all together (details in follow-up patch) > > yet not all userspace checks if it's authenticated, but instead uses > > uncommon assumptions. > > > > After days of digging through git log and testing, only a single (ab)use > > was spotted - the Mesa RADV driver, using the AMDGPU_INFO ioctl and > > assuming that failure implies lack of authentication. > > Maybe correction here: Id does not care about authentication at all. It > wants to figure out whether it has access to modeset resources, which is > something entirely different, but happened to match in amdgpu's case. > It feels like we have conflated the two (perhaps due to historical reasons) and I'm not 100% sure which one the AMDGPU code inspects. How about: Hence we can drop the DRM_AUTH all together (details in follow-up patch) yet that cause a regression in some userspace, when it conflates the authentication status with access to modeset resources. After days of digging through git log and testing, only a single (ab)use was spotted - the Mesa RADV driver, using the AMDGPU_INFO ioctl. > > Affected versions are: > > - the whole 18.2.x series, which is EOL > > - the whole 18.3.x series, which is EOL > > - the 19.0.x series, prior to 19.0.4 > > Hm I think I'm blind, I'm not seeing the fix merged to mesa master. Still > there on gitlab: > > https://gitlab.freedesktop.org/mesa/mesa/blob/master/src/amd/vulkan/radv_device.c#L291 > > What am I missing? > Opted for a simple, more generic solution see commit c962a78f18284e2971301bf68c9c60500ca398e4 This way, the same check is: - enforced where it's used - present for all Mesa Vulkan drivers Will include the sha + commit title for v2. > > Add a special quirk for that case, thus we can drop DRM_AUTH bits as > > mentioned earlier. > > > > Since all the affected userspace is EOL, we also add a kconfig option > > to disable this quirk. > > > > The whole approach is inspired by DRIVER_KMS_LEGACY_CONTEXT > > > > Cc: Alex Deucher <alexander.deucher@xxxxxxx> > > Cc: Christian König <christian.koenig@xxxxxxx> > > Cc: amd-gfx@xxxxxxxxxxxxxxxxxxxxx > > Cc: David Airlie <airlied@xxxxxxxx> > > Cc: Daniel Vetter <daniel@xxxxxxxx> > > Signed-off-by: Emil Velikov <emil.velikov@xxxxxxxxxxxxx> > > Aside from the nits I think reasonable approach. Great, glad to hear. Now all we need is to bribe^Wconvince Christian. Thanks Emil _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
