Changing the root password in recent SmartOS

Back in 2012 Jonathan Perkin wrote a little bit about SmartOS and the global zone, why and what in SmartOS is mounted read-only.

Back then /etc/shadow, the file containing the root password, was mounted with write permissions. It is not anymore:

# ls -l /etc/shadow
-r--------   1 root     root         560 May 12 19:51 /etc/shadow

And thus passwd will fail when trying to change the password. But it's easy to circumvent this. It's actually a lofs-mount as can be seen:

# mount | grep shadow
/etc/shadow on /usbkey/shadow read/write/setuid/devices/dev=1690008 on Mon May 12 20:05:36 2014

So to change your password use the following:

/usr/lib/cryptpass your-fancy-password
# replace crypt string in /usbkey/shadow
umount /etc/shadow
mount -F lofs /usbkey/shadow /etc/shadow
  1. will create the crypt string of your password. Make sure to remove it from your bash history afterwards
  2. place this string in /usbkey/shadow (it's the long string between the first two :)
  3. unmount the file in place
  4. remount the right file back in place

And that's it, the new root password is set.