From a19afebb883f2a02ecf4b8d5a114ce6957a59238 Mon Sep 17 00:00:00 2001 From: Thomas Hellstrom Date: Wed, 26 Aug 2015 05:49:21 -0700 Subject: [PATCH 2/2] drm/vmwgfx: Allow dropped masters render-node like access on legacy nodes v2 Applications like gnome-shell may try to render after dropping master privileges. Since the driver should now be safe against this scenario, allow those applications to use their legacy node like a render node. v2: Add missing return statement. Signed-off-by: Thomas Hellstrom Reviewed-by: Sinclair Yeh --- drivers/gpu/drm/vmwgfx/vmwgfx_drv.c | 7 ++++++- drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 6 ++++++ 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c index a4766acd0ea2..d022b509f1ac 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c @@ -993,10 +993,15 @@ static struct vmw_master *vmw_master_check(struct drm_device *dev, } /* - * Check if we were previously master, but now dropped. + * Check if we were previously master, but now dropped. In that + * case, allow at least render node functionality. */ if (vmw_fp->locked_master) { mutex_unlock(&dev->master_mutex); + + if (flags & DRM_RENDER_ALLOW) + return NULL; + DRM_ERROR("Dropped master trying to access ioctl that " "requires authentication.\n"); return ERR_PTR(-EACCES); diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c index 4d0c98edeb6a..7fc3e8abd0c4 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c @@ -906,6 +906,12 @@ vmw_surface_handle_reference(struct vmw_private *dev_priv, "surface reference.\n"); return -EACCES; } + if (ACCESS_ONCE(vmw_fpriv(file_priv)->locked_master)) { + DRM_ERROR("Locked master refused legacy " + "surface reference.\n"); + return -EACCES; + } + handle = u_handle; } -- 2.4.3