Re: sharing one r/w unix filesystem between different machines and users

[Christoph Groth <cwg@falma.de>]

"Robert Blair Mason Jr." <rbmj@verizon.net> writes:

> Christoph Groth <cwg@falma.de> wrote:
>
>> Blair Mason <rbmj@verizon.net> writes:
>> 
>> > Permission schemes on removable media are not too powerful annyway,
>> > as anyone with root on any machine can change them... my $0.02.
>> 
>> Exactly -- I wonder whether there are any decent (modern features,
>> public specification, nice free implementation, etc.) filesystems
>> which allow to ignore permissions when mounted by a user.
>> 
> Will something like the following work? This works on any filesystem
> using standard unix permissions (such as ext*, ufs, reiserfs*, btrfs,
> etc.)
>
> Suppose your filesystem is mounted on /media/usb0.
>
> # chmod -R a+rwx /media/usb0
>
> This does, however, seem the Wrong Way To Do It, as it will not work
> for files created after issuing the command.

That's the point.  If user A creates some directory, and user B (who has
a different uid on his machine) wants to delete a file in this
directory, user B will have first to become root and override the
permissions.  This is an unnecessary hassle and requires the user in
question to be fairly technical.  And it won't work if the user is
unable to become root.

> Unfortunately, there isn't an elegant way to do this. It seems like it
> should be an option to mount (something like ignoreperms).  Looking at
> the internet, it appears that OSX has a mount option to do this:
>
> http://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man8/mount.8.html
> (search for 'noowners')
>
> This option does not appear to exist on Linux or BSD, however.

Thanks, I've been looking for something like this (though an OSX
solution doesn't help me).  I really wonder why no one has ever fixed
this issue for Linux -- probably everybody is happy simply using FAT and
NTFS on shared removable media.  And their importance is fading anyway.

Thanks,
Christoph