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 <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
index 03854d6..e13b20b 100644 (file)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
@@ -1052,10 +1052,15 @@ 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 5b8595b..3361769 100644 (file)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
@@ -911,6 +911,12 @@ 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;
        }