Re: RFC: usermount - a secure mount for unpriviledged users

["U.Mutlu" <for-gmane@mutluit.com>]

Karel Zak wrote on 11/19/2015 12:05 PM:
> On Wed, Nov 18, 2015 at 06:17:12PM +0100, U.Mutlu wrote:
>> Currently no responsible admin can grant permission to the mount pgm
>> to his users, because of the dangers inherent with bind-mounting etc.
>
> man mount, "The non-superuser mounts." section.
>
>      Karel

The man page says:
  The non-superuser mounts.
  Normally, only the superuser can mount filesystems. However, when fstab
  contains the user option on a line, anybody can mount the corresponding 
filesystem.

Ok, let's try this out:

/etc/fstab:
...
/home/userx/tmp/myfs1.img /home/userx/tmp/mymnt1 auto user,noauto 0 0
/home/userx/tmp/myfs2.img /home/userx/tmp/mymnt2 auto user,noauto 0 0

userx@mach:~/tmp$ ls -l
-rw-r--r-- 1 userx userx 10485760 Nov 19 02:11 myfs1.img
-rw-r--r-- 1 userx userx 10485760 Nov 17 07:20 myfs2.img
drwxr-xr-x 2 userx userx     4096 Nov 19 18:38 mymnt1
drwxr-xr-x 2 userx userx     4096 Nov 19 18:38 mymnt2

userx@mach:~/tmp$ mount /home/userx/tmp/myfs1.img /home/userx/tmp/mymnt1
mount: only root can do that

So, then why is this not working?