drm/ttm: ttm object security fixes for render nodes

When a client looks up a ttm object, don't look it up through the device hash
table, but rather from the file hash table. That makes sure that the client
has indeed put a reference on the object, or in gem terms, has opened
the object; either using prime or using the global "name".

To avoid a performance loss, make sure the file hash table entries can be
looked up from under an RCU lock, and as a consequence, replace the rwlock
with a spinlock, since we never need to take it in read mode only anymore.

Finally add a ttm object lookup function for the device hash table, that is
intended to be used when we put a ref object on a base object or, in  gem terms,
when we open the object.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
index 7de2ea8bd553..0fc93398bba2 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
@@ -843,6 +843,7 @@ out_unlock:
 int vmw_surface_reference_ioctl(struct drm_device *dev, void *data,
                                 struct drm_file *file_priv)
 {
+        struct vmw_private *dev_priv = vmw_priv(dev);
         union drm_vmw_surface_reference_arg *arg =
             (union drm_vmw_surface_reference_arg *)data;
         struct drm_vmw_surface_arg *req = &arg->req;
@@ -854,7 +855,7 @@ int vmw_surface_reference_ioctl(struct drm_device *dev, void *data,
         struct ttm_base_object *base;
         int ret = -EINVAL;
 
-        base = ttm_base_object_lookup(tfile, req->sid);
+        base = ttm_base_object_lookup_for_ref(dev_priv->tdev, req->sid);
         if (unlikely(base == NULL)) {
                 DRM_ERROR("Could not find surface to reference.\n");
                 return -EINVAL;