[lug] Allowing Users to Supermount

Todd Ruskell truskell at Mines.EDU
Sun Feb 25 22:06:44 MST 2001

In addition to Alan's comments, you can also include a umask option to
mount, or in your fstab, depending on your needs.  For example, the
following line in fstab allows full rwx access to the mount point.

/dev/hda5	/DriveD		vfat	defaults,umask=0000		0

As always, beware of the security problems associate with this.  However,
I believe you can also specify both a user and a group with the mount
command, as well.  Combined with an appropriate umask, you should be able
to get what you need.


On Sun, 25 Feb 2001, Alan Robertson wrote:

> SoloCDM wrote:
> >
> > How do I allow specified users access to a supermounted cdrom
> > (iso9660)?
> >
> > Every time I "ls -A" /[mount_directory], from a user account,
> > I get: ls: /[mount_directory]: Permission denied.  I tried adding
> > permissions for the user to group adm, disk, cdrom.  I changed the
> > permissions for /dev/hdd to 666, 644, 655.  I tried mounting the
> > cdrom with supermount disabled and I get: mount: /dev/hdd already
> > mounted or /[mount_directory] busy.  The first bit, after switching
> > everything back to the original settings, is set to: brw-------,
> > which I surmised must be the reason for the "busy" message, because
> > I didn't find any reference for "b".
> >
> > BTW, what is the chmod mode or octal_mode for "b"?
> "b" means block special device.  It means it's a disk like device.  Trust
> me, you don't want to change that.
> The mount system call is just plain restricted to the superuser.  Device
> permissions don't matter.  However, the /sbin/mount command can have a flag
> in it called user which will allow mere mortals to perform the requested
> mount operation.
> >From the "mount(8)" man page while talking about /etc/fstab:
>   (iii) Normally, only the superuser can mount file systems.
>        However, when fstab contains the user option  on  a  line,
>        then anybody can mount the corresponding system.
>        Thus, given a line
>               /dev/cdrom  /cd  iso9660  ro,user,noauto,unhide
>        any  user  can  mount the iso9660 file system found on his
>        CDROM using the command
>               mount /dev/cdrom
>        or
>               mount /cd
> OK?
> 	-- Alan Robertson
> 	   alanr at unix.sh
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