support: Helper functions for entering namespaces

1 files changed, 40 insertions, 0 deletions

diff --git a/support/support_become_root.c b/support/support_become_root.c
new file mode 100644
index 0000000000..d13954c4dd
--- /dev/null
+++ b/support/support_become_root.c
@@ -0,0 +1,40 @@
+/* Acquire root privileges.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/namespace.h>
+
+#include <sched.h>
+#include <stdio.h>
+#include <unistd.h>
+
+bool
+support_become_root (void)
+{
+#ifdef CLONE_NEWUSER
+  if (unshare (CLONE_NEWUSER | CLONE_NEWNS) == 0)
+    /* Even if we do not have UID zero, we have extended privileges at
+       this point.  */
+    return true;
+#endif
+  if (setuid (0) != 0)
+    {
+      printf ("warning: could not become root outside namespace (%m)\n");
+      return false;
+    }
+  return true;
+}