can't mount if user is among a random group

nass · 02-07-2007, 06:56 PM

hi everyone,
i have this situation and i do not know where im thinking wrongly.

up until now, i have te following entry in my fstab file:
/dev/sdb1 /mnt/memstick auto noauto,owner,users,rw 0 0

so users of te groups 'users' can mount a flash device.

to keep things nice and clean i decided to add a group 'flash' who's members will have access to a flash memory. so as to restrict some members of the group 'users' to have access to the memory stick.

so i replaces the word 'users' in the fstab entry shown above with 'flash' (from te group) and i also chgrp of /dev/sdb1 to flash. i thought that would do it but it didn't.. what am i forgeting?
nass

gilead · 02-07-2007, 07:09 PM

I can't get to a box here to check this on, but the following /etc/fstab entry should work since the group option is the one to specify that group membership must be checked:

Code:

/dev/sdb1 /mnt/memstick auto noauto,group,rw 0 0

gnashley · 02-08-2007, 02:04 PM

That entry in fstab isn't for the group 'users'. Notice that you can use 'user' as well. Using 'user' in fstab options means that only the smae person who mounted the device can unmount it. If yopu use 'user' then anyone can unmount it. If you want to control access to the device in fstab, try using uid= or gid= in the options.

nass · 02-09-2007, 04:38 AM

yes, in the end

Code:

/dev/flash   /mnt/memstick    auto    noauto,owner,group,rw      0   0

did the work.where:

Code:

root@meditSea:/# ls -l /dev/flash
lrwxrwxrwx  1 root flash 9 2007-02-09 12:33 /dev/flash -> /dev/sdb1

and

Code:

root@meditSea:/# ls -l /dev/sdb1
brw-rw----  1 root flash 8, 17 1995-04-29 13:34 /dev/sdb1

similarly for the cdrom

Code:

/dev/cdrom    /mnt/cdrom   auto   noauto,owner,group,ro  0   0

with:

Code:

root@meditSea:/# ls -l /dev/cdrom
lrwxrwxrwx  1 root cdrom 8 2007-02-03 15:32 /dev/cdrom -> /dev/hda
root@meditSea:/# ls -l /dev/hda
brw-rw----  1 root cdrom 3, 0 2002-06-09 22:27 /dev/hda

i didn't more into uid and gid features as its a home computer and i won't be needing the additional hassle

thank you boht your help.
nass

gnashley · 02-09-2007, 05:48 AM

What you decribe works when you put each user in the group that owns the device. then the owner(root) or any mamber of that group can mount unmount.
Usually for home systems you'd just use 'user' or 'users' to give users access.

TSquaredF · 02-09-2007, 08:21 AM

If you are using a 2.4 series kernel, quit reading, but making your own links with a 2.6 series kernel will fail when the system is rebooted, because /dev is is ram based & not persistent from session to session. You need to write a new udev rule to cover your requirements, or just use "users", as gnashley has suggested.
Regards,
Bill

rworkman · 02-11-2007, 01:27 AM

Quote:

Originally Posted by nass

hi everyone,
i have this situation and i do not know where im thinking wrongly.

up until now, i have te following entry in my fstab file:
/dev/sdb1 /mnt/memstick auto noauto,owner,users,rw 0 0

so users of te groups 'users' can mount a flash device.

to keep things nice and clean i decided to add a group 'flash' who's members will have access to a flash memory. so as to restrict some members of the group 'users' to have access to the memory stick.

so i replaces the word 'users' in the fstab entry shown above with 'flash' (from te group) and i also chgrp of /dev/sdb1 to flash. i thought that would do it but it didn't.. what am i forgeting?
nass

See http://slackwiki.org/Windows_Partitions

RW

nass · 02-14-2007, 02:30 AM

Quote:

Originally Posted by TSquaredF

If you are using a 2.4 series kernel, quit reading, but making your own links with a 2.6 series kernel will fail when the system is rebooted, because /dev is is ram based & not persistent from session to session. You need to write a new udev rule to cover your requirements, or just use "users", as gnashley has suggested.
Regards,
Bill

actually i am writing to say eexactly that.
while /dev/flash is owned by root flash,
/dev/sdb1 that it points to on reboot is root disk, not root flash as i set it.
which is kind of irritating since i basically lose the functionality.

ganshley where do you suggest i put the 'users' keyword ?
instead of 'group' in fstab? cause i thought the keyword in fstab that enabled groups checking is 'group' ...

gnashley · 02-14-2007, 04:29 AM

Yes, the easy way is to use 'users' or 'user' instead of 'group' in the fstab mount options field.
If you put 'user' only the person who mounts the device will be able to unmount it. If you put 'users' then any user can unmount the devide, even if another user mounted it.
Links that you create to /dev files shouldn't affect the real device, because links are always rwxrwxrwx (777) anyway.