rune/libenclave: Initialize nss libraries in Glibc

So that the dynamic libraries are loaded in the host. The fix refers
to https://github.com/moby/moby/pull/39612/commits/a316b10dab79d9298b02c7930958ed52e0ccf4e4Signed-off-by: Jia Zhang <zhang.jia@linux.alibaba.com>

rune/libenclave/init.go

@@ -3,6 +3,8 @@ package libenclave // import "github.com/opencontainers/runc/libenclave"
 import (
 	"github.com/opencontainers/runc/libcontainer/configs"
 	"github.com/opencontainers/runc/libenclave/intelsgx"
+	"net"
+	"os/user"
 )
 
 var (
@@ -31,6 +33,11 @@ func IsEnclaveHwEnabled(etype string) bool {
 }
 
 func init() {
+	// initialize nss libraries in Glibc so that the dynamic libraries are loaded in the host
+	// environment not in the chroot from untrusted files.
+	_, _ = user.Lookup("")
+	_, _ = net.LookupHost("")
+
 	if intelsgx.IsSgxSupported() {
 		enclaveHwType = configs.EnclaveHwIntelSgx
 	}