support/support_enter_mount_namespace.c

   1 /* Enter a mount namespace.
   2    Copyright (C) 2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <support/namespace.h>
  20
  21 #include <sched.h>
  22 #include <stdio.h>
  23 #include <sys/mount.h>
  24
  25 bool
  26 support_enter_mount_namespace (void)
  27 {
  28 #ifdef CLONE_NEWNS
  29   if (unshare (CLONE_NEWNS) == 0)
  30     {
  31       /* On some systems, / is marked as MS_SHARED, which means that
  32          mounts within the namespace leak to the rest of the system,
  33          which is not what we want.  */
  34       if (mount ("none", "/", NULL, MS_REC | MS_PRIVATE, NULL) != 0)
  35         {
  36           printf ("warning: making the mount namespace private failed: %m\n");
  37           return false;
  38         }
  39       return true;
  40     }
  41   else
  42     printf ("warning: unshare (CLONE_NEWNS) failed: %m\n");
  43 #endif /* CLONE_NEWNS */
  44   return false;
  45 }