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Old 08-28-2005, 01:10 AM   #1
Registered: Aug 2005
Distribution: Ubuntu Intrepid and Meerkat, formerly used Debian 3.1 (Sarge) with Gnome Desktop
Posts: 353

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How to Adjust permissions for a mounted windows fat32 filesystem

I have a windows filesystem mounted, which mounts at bootup.

When logged in as a user (not root), I can view and navigate through the folders but cannot copy files to it.

have tried chmod a=rwx foo but it doesn't change the permissions

Has anyone got a solution to allow a user to be able to write to the windows file system?
Old 08-28-2005, 02:13 AM   #2
Red Hat India
Registered: Nov 2004
Location: Kerala/Pune,india
Distribution: RedHat, Fedora
Posts: 260

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writing to a mounted windows filesystem is still not practical, especially if its an ntfs one. for an ordinary user to copy files from win partition, you have to log in as root and change the permissions of the mount point 644. this will make copying files possible.
Old 08-28-2005, 02:21 AM   #3
Registered: Dec 2003
Location: Kansai, Japan
Distribution: LFS, FedoraCore
Posts: 35

Rep: Reputation: 15
Modify fstab

I had the same problem.

To fix this, modify /etc/fstab to include "umask=000". Here's what (some of) mine looks like:

# This file is edited by fstab-sync - see 'man fstab-sync' for details
LABEL=/                 /                       ext3    defaults        1 1
/dev/hdb3               /WinXP                  vfat    users,umask=000 0 0
/dev/devpts             /dev/pts                devpts  gid=5,mode=620  0 0
/dev/shm                /dev/shm                tmpfs   defaults        0 0
LABEL=/home             /home                   ext3    defaults        1 2
/dev/proc               /proc                   proc    defaults        0 0
/dev/sys                /sys                    sysfs   defaults        0 0
LABEL=SWAP-hdb5         swap                    swap    defaults        0 0
/dev/fd0                /media/floppy           auto    pamconsole,exec,noauto,managed 0 0
/dev/hdc                /media/cdrecorder       auto    pamconsole,exec,noauto,managed 0 0
I showed you most of the file so you won't be intimidated by seeing the whole thing if you've never opened it before.

Pay special attention to the third line, starting with /dev/hdb3 . This is the line that indicates my shared vfat (FAT32) partition. Most of my partitions say default after the file system type, but this one in particular says users,umask=000. That is what gives the entire volume read, write and execute permissions to everyone.

That is not a secure way of doing things, particularly if you are sharing the entire windows tree, including whatever volume stores the windows system files. Someone (in this case anyone) could write a virus, corrupt data, delete, etc the entire volume. So be sure this is a separate, shared partition, not a part of your Windows system tree.

FAT partitions do not support individual file and folder permissions, so there is no way to grant a specific user permissions of any sort to a specific file or folder. That means that whatever permissions you grant for the volume exist throughout the entire volume. So be choosey unless you are in a situation where you know everyone who is using that particular system (like in my case where it is just me and my girls... at home, not in an office full of people). In addition, since VFAT does not really support permissions, the Linux system itself is doing the granting, based on whoever mounted the partition. In the case of an installation-script produced fstab, the volume is mounted at boot time, which means the user listed as mounting it is root. After mount, noone can genuinely modify the file permissions with chown (or any other ch~ command) because the file system does not support this use. So you're stuck with root and only root being able to edit anything on the shared partition.

That's one of the big reasons we've moved away from VFAT... including MS's shift to NTFS. That's the sort of inconsistency you get when you have a file system that was designed for a non-networked Disk Operating System (i.e. single-user system) where the only security layer is physical access and single-superuser login to the system that must operate in an environment that is suddenly security-oriented and highly networked.

If you want to know more, and get more in-depth modifying exactly who can do what on your system, do some research on the fstab file, and exactly what all the numbers and permission tags mean.

Last edited by TheGiantPotato; 08-28-2005 at 02:23 AM.


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