[lxc-devel] Permission of /dev/null to 0600 when booting daemon mode without logging

[Ryousei Takano]

Hi daniel and all,

I have ran the CentOS 5 container on the CentOS 5.  When lxc-start executes with daemon mode
and without logging, the permission of /dev/null on the host OS changes from 0666 to 0600.

I guess it is because lxc uses bind mount due to remap from /dev/console to /dev/null with daemon 
mode.  The container OS changes the permission of /dev/console at its boot process, and then it 
influences /dev/null on the host OS.

I do not know whether this problem occurs on the other distros.

Here is a simple reproduction code:

#include <stdio.h>
#include <unistd.h>
#include <sys/mount.h>

int
main()
{
 /* [LXC] setup_console (lxc/conf.c) */
 if (mount("/dev/null", "/dev/console", "none", MS_BIND, 0)) { /* (1) */
   perror("mount");
   return -1;
 }
 /* [CentOS] ??? */
 if (chmod("/dev/console", 0600)) { /* (2) */
   perror("chmod");
   return -1;
 }
 if (umount("/dev/console")) {
   perror("umount");
   return -1;
 }
 return 0;
}

Any comments and suggestions will be welcome.
Thanks,
Ryousei