[PATCH 1/3] drm/vmwgfx: check master authentication in surface_ref ioctls

[Emil Velikov]

From: Emil Velikov <emil.velikov at collabora.com>

With later commit we'll rework DRM core authentication handling.

Namely unauthenticated master will be allowed with, DRM_AUTH ioctls.
Since vmwgfx does additional master locking and DRM_AUTH handling, this
will not matter almost all cases.

The only exception being using the legacy handle type in the family of
surface_reference iocts - all handled by vmw_surface_handle_reference().
Add the check to ensure such clients do not access more than they should

Cc: VMware Graphics <linux-graphics-maintainer at vmware.com>
Cc: Thomas Hellstrom <thellstrom at vmware.com>
Signed-off-by: Emil Velikov <emil.velikov at collabora.com>
---
I'd like to merge this through the drm-misc tree. Ack and rb are
appreciated.

Thanks
Emil

Unrelated: worth moving the is_render_client check alongside the
is_primary_client one.
---
 drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
index 219471903bc1..1f5146c95785 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
@@ -940,6 +940,13 @@ vmw_surface_handle_reference(struct vmw_private *dev_priv,
 		user_srf = container_of(base, struct vmw_user_surface,
 					prime.base);
 
+		/* Error out if we are unauthenticated master */
+		if (drm_is_primary_client(file_priv) &&
+		    !file_priv->authenticated) {
+			ret = -EACCES;
+			goto out_bad_resource;
+		}
+
 		/*
 		 * Make sure the surface creator has the same
 		 * authenticating master, or is already registered with us.
-- 
2.21.0