permissions for USB and "media" drives

SaintDanBert · 01-21-2010, 11:33 AM

How do I configure permissions and ownership [aka, access control] for USB and other "media" drives? In general, I want the plain user to have read-write-modify access. For the long haul, I would prefer some sort of config table that says this media gets those access settings on an individual basis.

While on the subject of "media" drives, how do I configure where a drive gets mounted? It appears that the defaults is /media/someString where "someString" is either a generated string or the volume label. Is this accomplished by a script somewhere that I might modify or configure?

I login using my personal, non-root account. When I connect a USB or other "media" drive, the permissions and ownership are such that I cannot use the desktop tools to alter the drive contents. Also, I need to guess where a given drive contents can be found.

~~~ 0;-Dan

guard · 01-21-2010, 11:53 AM

If you use udev+hal (most probably it's so if you use modern out of the box distro), read this thread: http://forums.fedoraforum.org/showthread.php?t=152328

nkd · 01-21-2010, 12:25 PM

If you login as non root user in the gui , and ain't able to use the gui interface to manage the device, try opening a terminal, change over to root user using sudo and open the browser from terminal window as under :-
nautilus "name of the mounted media"
example :-
nautilus /dev/sdc1 ; for my usb pen drive.

Even gedit "filename on the media" will open the file in rw mode in gui.

hope that helps
nishith

kyphi · 01-21-2010, 04:15 PM

Mounting should be automatic.

To check that you have the necessary privileges, go to System, Administration, Users and Groups. Unlock the screen with your password, single click on your name, single click on Properties. When the Account Properties screen opens, select the User Privileges tab and ensure that "Access external storage devices automatically" is ticked.

As administrator you can set these permissions on an individual basis.

SaintDanBert · 01-23-2010, 11:25 PM

Folks, I appreciate all of your comments, but didn't answer the question (blush) that I meant to ask.

Over here I have some USB drive. I want user=joe to have this access and user=mary to have that access. For some other USB drive I want user=joe and user=mary to have different access or no-access to the drive. In a script, this might be nested switch-case statements:

Code:

# pseudo-code
switch (USB drive)
{
  case (drive 'a')
  {
    testUser( 'x' )
  }
  ...
  default( * )
  {
    testUser( 'x' }
  }
  
}

... or something like that.

~~~ 0;-Dan

slightlystoopid · 01-24-2010, 01:55 AM

I haven't tried this, buuut in Ubuntu you might try:

Giving the usb sticks labels. For an ext# partition, if you didn't set a label, you can do so this way:

sudo tune2fs -L "yolabel" /dev/yousb

For vfat, you can get the current label with:

mlabel -s /dev/yousb

Now configure nautilus not to mount junk:

gconftool-2 -t bool -s /apps/nautilus/preferences/media_automount_open false
gconftool-2 -t bool -s /apps/nautilus/preferences/media_automount false

Now, modify your fstab to look for these labels and not a device, as well as a specific user id. something like, perhaps:

yolabel1 /media/usb type user,noauto,uid=UID1 0 0
yolabel2 /media/usb type user,noauto,uid=UID2 0 0

Julyan · 01-24-2010, 09:15 PM

As root see which groups are available in /etc/group.
Then (as root) do:
useradd (or adduser) <user> -G <list of groups separated by commas>.
For example:
useradd timmy -G audio,cdrom, ...
This will let user timmy use audio, cdrom, etc.

Hope it helps.

guard · 01-25-2010, 02:08 AM

Dan, I believe that all of these can be done with the HAL configuration, though it might be quite advanced. But the task itself is quite advanced.