Use libcontainer execseal to run ldconfig

This change copies ldconfig into a memfd before executing it from
the createContainer hook.

Signed-off-by: Evan Lezar <elezar@nvidia.com>

cmd/nvidia-cdi-hook/update-ldcache/safe-exec_linux.go

@@ -0,0 +1,57 @@
+/**
+# Copyright (c) 2025, NVIDIA CORPORATION.  All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+**/
+
+package ldcache
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"syscall"
+
+	"github.com/opencontainers/runc/libcontainer/dmz"
+)
+
+// SafeExec attempts to clone the specified binary (as an memfd, for example) before executing it.
+func (m command) SafeExec(path string, args []string, envv []string) error {
+	safeExe, err := cloneBinary(path)
+	if err != nil {
+		m.logger.Warningf("Failed to clone binary %q: %v; falling back to Exec", path, err)
+		//nolint:gosec // TODO: Can we harden this so that there is less risk of command injection
+		return syscall.Exec(path, args, envv)
+	}
+	defer safeExe.Close()
+
+	exePath := "/proc/self/fd/" + strconv.Itoa(int(safeExe.Fd()))
+	//nolint:gosec // TODO: Can we harden this so that there is less risk of command injection
+	return syscall.Exec(exePath, args, envv)
+}
+
+func cloneBinary(path string) (*os.File, error) {
+	exe, err := os.Open(path)
+	if err != nil {
+		return nil, fmt.Errorf("opening current binary: %w", err)
+	}
+	defer exe.Close()
+
+	stat, err := exe.Stat()
+	if err != nil {
+		return nil, fmt.Errorf("checking %v size: %w", path, err)
+	}
+	size := stat.Size()
+
+	return dmz.CloneBinary(exe, size, path, os.TempDir())
+}

cmd/nvidia-cdi-hook/update-ldcache/safe-exec_other.go

@@ -0,0 +1,29 @@
+//go:build !linux
+// +build !linux
+
+/**
+# Copyright (c) 2025, NVIDIA CORPORATION.  All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+**/
+
+package ldcache
+
+import "syscall"
+
+// SafeExec is not implemented on non-linux systems and forwards directly to the
+// Exec syscall.
+func (m *command) SafeExec(path string, args []string, envv []string) error {
+	//nolint:gosec // TODO: Can we harden this so that there is less risk of command injection
+	return syscall.Exec(path, args, envv)
+}

cmd/nvidia-cdi-hook/update-ldcache/update-ldcache.go

@@ -22,7 +22,6 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
-	"syscall"
 
 	"github.com/urfave/cli/v2"
 
@@ -143,8 +142,7 @@ func (m command) run(c *cli.Context, cfg *options) error {
 	// be configured to use a different config file by default.
 	args = append(args, "-f", "/etc/ld.so.conf")
 
-	//nolint:gosec // TODO: Can we harden this so that there is less risk of command injection
-	return syscall.Exec(ldconfigPath, args, nil)
+	return m.SafeExec(ldconfigPath, args, nil)
 }
 
 // resolveLDConfigPath determines the LDConfig path to use for the system.