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Re: how to format a floppy in ext2



On Sat, Mar 31, 2001 at 02:16:32PM +0200, Robert Voigt wrote:
>  > > I think you need to chage the permissions of the /floppy directory...
>  > >
>  > >
>  > > chmod g+w /floppy    .....if that doesn't work try
>  > > chmod a+w /floppy
> 
> The chmod did the trick. How could I forget the permissions? I was 
> confused because I could write to msdos floppies without having write 
> access to /floppy, wierd.

its not wierd at all, msdos floppies have no permissions so they are
faked, whoever mounts it gets to be the fake owner.  

with ext2 it has real support for real permissions, so they are
respected like any other filesystem.  it doesn't matter who mounts
it.  

though on removable media it perhaps might be useful to have a
ignoreperms,uid=XXX type mount options since uids often don't match
across systems (unless nis, or some manual effort is taken).  

> I cannot run mke2fs as user, only as root. I don't know if it's a good 
> idea to change the permissions for mke2fs (I'm connected to the internet 
> = security risk). Anyway, there's no difference in write access to the 
> floppy, regardless who formatted it. Also the permissions for /dev/fd0 
> seem to have no effect, only those for /floppy.

you do have permissions to mke2fs, its just not in your PATH.  try
/sbin/mke2fs /dev/fd0.  

what you DO need permissions on is the /dev/fd0 device, which is by
default 660 root.floppy.  if you are a member of the floppy group you
can format and create filesytstems on the floppy.  i don't think its
much of a risk to add your account to the floppy group.  i would not
add anyone else (untrusted lusers) since there are many trivial ways
to crash the system when you have both the ability to mount a device
and the ability to write directly to the device.  

with ext2 floppies you just need to manage permissions and owners like
any other part of your filesystem.  so mke2fs as root, mount it and
chown it to yourself, or twiddle the group and change permissions as
appropriate.  

-- 
Ethan Benson
http://www.alaska.net/~erbenson/

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