@@ -43,6 +43,7 @@ const gchar *create_tmpdir() {
4343void pivot_host(const gchar *guest) {
4444 g_autofree gchar *point = g_build_filename(guest, "host", NULL);
4545 fail_if(g_mkdir(point, 0755));
46+ fail_if(mount(0, "/", 0, MS_PRIVATE | MS_REC, 0));
4647 fail_if(pivot_root(guest, point));
4748}
4849
@@ -56,6 +57,7 @@ void bind_mount_item(const gchar *host, const gchar *guest, const gchar *name) {
5657
5758void bind(const gchar *host, const gchar *guest) {
5859 mount_tmpfs(guest);
60+
5961 pivot_host(guest);
6062
6163 g_autofree gchar *host_dir = g_build_filename("/host", host, NULL);
@@ -105,7 +107,11 @@ int main(gint argc, gchar **argv) {
105107 uid_t uid = getuid();
106108 gid_t gid = getgid();
107109
108− if (unshare(CLONE_NEWNS | CLONE_NEWUSER) < 0) {
110+ int namespaces = CLONE_NEWNS;
111+ if (uid != 0) {
112+ namespaces |= CLONE_NEWUSER;
113+ }
114+ if (unshare(namespaces) < 0) {
109115 int unshare_errno = errno;
110116
111117 g_message("Requires Linux version >= 3.19 built with CONFIG_USER_NS");
@@ -116,9 +122,11 @@ int main(gint argc, gchar **argv) {
116122 fail("unshare", unshare_errno);
117123 }
118124
119− spit("/proc/self/setgroups", "deny");
120− spit("/proc/self/uid_map", "%d %d 1", uid, uid);
121− spit("/proc/self/gid_map", "%d %d 1", gid, gid);
125+ if (uid != 0) {
126+ spit("/proc/self/setgroups", "deny");
127+ spit("/proc/self/uid_map", "%d %d 1", uid, uid);
128+ spit("/proc/self/gid_map", "%d %d 1", gid, gid);
129+ }
122130
123131 // If there is a /host directory, assume this is nested chrootenv and use it as host instead.
124132 gboolean nested_host = g_file_test("/host", G_FILE_TEST_EXISTS | G_FILE_TEST_IS_DIR);