[PATCH 2/5] 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 authentication handling. Namely
DRM_AUTH will not be a requirement for DRM_RENDER_ALLOW ioctls.

Since vmwgfx does isolation for primary clients in different master
realms, the DRM_AUTH can be dropped.

The only place where authentication matters, is surface_reference ioctls
whenever a legacy (non-prime) handle is used. For those ioctls we call
vmw_surface_handle_reference(), where we explicitly check if the client
is both a) master and b) unauthenticated - bailing out as result.

Otherwise the usual isolation path kicks in and we're all good.

v2: Reword commit message, since the isolation work has landed.

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>
---
 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 1f989f3605c8..596e5c1bc2c1 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
@@ -936,6 +936,13 @@ 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.
-- 
2.23.0