--- cifs-utils-5.0.orig/cifs.upcall.c	2011-06-01 20:41:44.000000000 +0100
+++ cifs-utils-5.0/cifs.upcall.c	2011-09-21 15:00:58.000000000 +0100
@@ -327,6 +327,7 @@ static int
 cifs_krb5_get_req(const char *principal, const char *ccname,
 		  DATA_BLOB * mechtoken, DATA_BLOB * sess_key)
 {
+	char *qualified_principal;
 	krb5_error_code ret;
 	krb5_keyblock *tokb;
 	krb5_context context;
@@ -360,7 +361,44 @@ cifs_krb5_get_req(const char *principal,
 		goto out_free_ccache;
 	}
 
-	ret = krb5_parse_name(context, principal, &in_creds.server);
+	qualified_principal = (char*)principal;
+	if (!strchr(principal, '@')) {
+		char **realms, *realm;
+
+		ret = krb5_get_host_realm(context, principal, &realms);
+		if (ret) {
+			syslog(LOG_DEBUG, "%s: unable to get host realm (%s).",
+					__func__, principal);
+			goto out_free_principal;
+		}
+		if (realms && (realm = *realms)) {
+			int principal_len, realm_len, qualified_len;
+
+			syslog(LOG_DEBUG, "%s: got realm %s for principal %s",
+					__func__, realm, principal);
+			principal_len = strlen(principal);
+			realm_len = strlen(realm);
+			qualified_len = principal_len + 1 + realm_len + 1;
+			qualified_principal = calloc(sizeof(char),
+					qualified_len);
+			if (!qualified_principal) {
+				krb5_free_host_realm(context, realms);
+				goto out_free_principal;
+			}
+			strlcpy(qualified_principal, principal, qualified_len);
+			strlcpy(qualified_principal + principal_len, "@",
+					qualified_len - principal_len);
+			strlcpy(qualified_principal + principal_len + 1, realm,
+					qualified_len - principal_len - 1);
+			syslog(LOG_DEBUG, "%s: qualified principal is %s",
+					__func__, qualified_principal);
+		}
+		krb5_free_host_realm(context, realms);
+	}
+
+	ret = krb5_parse_name(context, qualified_principal, &in_creds.server);
+	if (qualified_principal != principal)
+		free(qualified_principal);
 	if (ret) {
 		syslog(LOG_DEBUG, "%s: unable to parse principal (%s).",
 		       __func__, principal);