From 420b84c0185123e9603dbab4303db79f3752cf73 Mon Sep 17 00:00:00 2001
From: Markus Lehtonen <markus.lehtonen@intel.com>
Date: Wed, 15 Oct 2025 09:43:06 +0300
Subject: [PATCH] Allow root CLOS in IntelRdt.closID

Enables:
    https://github.com/opencontainers/runtime-spec/pull/1289

Signed-off-by: Markus Lehtonen <markus.lehtonen@intel.com>
---
 pkg/cdi/container-edits.go      | 6 ++++--
 pkg/cdi/container-edits_test.go | 8 ++++++++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/pkg/cdi/container-edits.go b/pkg/cdi/container-edits.go
index 4744eff8..450a84f6 100644
--- a/pkg/cdi/container-edits.go
+++ b/pkg/cdi/container-edits.go
@@ -337,8 +337,10 @@ func ValidateIntelRdt(i *cdi.IntelRdt) error {
 
 // Validate validates the IntelRdt configuration.
 func (i *IntelRdt) Validate() error {
-	// ClosID must be a valid Linux filename
-	if len(i.ClosID) >= 4096 || i.ClosID == "." || i.ClosID == ".." || strings.ContainsAny(i.ClosID, "/\n") {
+	// ClosID must be a valid Linux filename. Exception: "/" refers to the root CLOS.
+	switch c := i.ClosID; {
+	case c == "/":
+	case len(c) >= 4096, c == ".", c == "..", strings.ContainsAny(c, "/\n"):
 		return errors.New("invalid ClosID")
 	}
 	return nil
diff --git a/pkg/cdi/container-edits_test.go b/pkg/cdi/container-edits_test.go
index ace0fd2e..c1fcfab0 100644
--- a/pkg/cdi/container-edits_test.go
+++ b/pkg/cdi/container-edits_test.go
@@ -254,6 +254,14 @@ func TestValidateContainerEdits(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "valid rdt config, root clos",
+			edits: &cdi.ContainerEdits{
+				IntelRdt: &cdi.IntelRdt{
+					ClosID: "/",
+				},
+			},
+		},
 		{
 			name: "invalid rdt config, invalid closID (slash)",
 			edits: &cdi.ContainerEdits{