linux-ext4 - Re: User permissions or UID/GIDs for portable disks?

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Date:	Thu, 1 Nov 2007 18:07:36 +0100
From:	"Bram Neijt" <bneijt@...il.com>
To:	linux-ext4@...r.kernel.org
Subject: Re: User permissions or UID/GIDs for portable disks?

Thanks to Dave and Eric for their replies.

I'm moving the feature discussion to a higher level (pmount) and I've
opened a blueprint on it[1] with more words on why I think it's a
problem[2].

This means that I'm leaving this thread and closing it with this mail.

I would like to thank everybody who replied and read this, for their help.

Greetings,
  Bram

[1] https://blueprints.launchpad.net/launchpad/+spec/usermount-permission-granting
[2] http://docs.google.com/Doc?id=dqqr5r6_41w7hfbx

On 10/25/07, Dave Kleikamp <shaggy@...ux.vnet.ibm.com> wrote:
> On Wed, 2007-10-24 at 19:38 -0700, Eric wrote:
> > On Wed, 2007-10-24 at 20:10 +0200, Bram Neijt wrote:
> > > One of the best solutions I can come up with is if the filesystem
> > > would allow for a switch that would help ignore these permissions as
> > > part of the filesystem.
> >
> > Ignoring file permissions on removable, user-supplied media sounds like
> > something that ought to be done above the level of individual
> > filesystems, just like how we ignore device files and suid/sgid files in
> > certain cases. Maybe this is something that ought to be one level up
> > from the ext2/3/4 filesystem driver?
>
> It would be a nice feature to implement at a higher level.  A lot of
> file systems do something like this.
>
> > In any case, this raises interesting questions. If we ignore permissions
> > on removable media, then anyone logged into your work computer (to which
> > you do not have root access) will be able to muck about with your files.
> > Is that something you want?
>
> Mount options should override on-media permissions, but those overriding
> permissions could still deny access to others:
>
> mount -o uid=1000,gid=1000,fmask=137,dmask=027 /dev/sdb1 /mnt/usbstick
>
> --
> David Kleikamp
> IBM Linux Technology Center
>
>
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