Re: [fuse-devel] fuse and glibc?

[Nescio N. <nes...@gm...>]

Thanks Michael, I hadn't heard of UnionFS before actually.  Sandboxie seems
to be somewhat different though.  You can 'sandbox' an application so that
its writes are redirected to some safe area on disk, but when you unsandbox
later, you can choose to either 'commit' some subset of the writes or
discard all of them.  Or is this possible with UnionFS too?  In either case
it's more of a tool than a filesystem.

I think I went off on a bit of a tangent though.  I wasn't investigating how
to build a Sandboxie-clone (although it sounds like fun) but whether or not
it is possible to break out of a FUSE filesystem that has been set as the
root filesystem.  What options are available to a regular user (not
superuser)?  Generalizing a bit further, I am curious about the limits of
FUSE's transparency.  For instance, there is a loopback filesystem example
in the FUSE tar.  It seems to just forward all the calls to the backing
filesystem.  Let's say I change the root to be this loopback filesystem.
Would any applications break?  If so, why?

On Mon, Nov 9, 2009 at 12:30 AM, Michael Raskin <fb0...@ra...> wrote:

> Jeffrey 'jf' Lim wrote:
> >> as the root filesystem.  How suitable is FUSE for implementing something
> >> like Sandboxie (http://www.sandboxie.com/)?  Has someone done this
> >> already?
> >>
> > a chroot would achieve the same thing. What would u specifically need
> fuse
> > for?
> >
> > -jf
>
> Well, it is convenient not to maintain chroots separately, but just
> configure unionfs writes and maybe shadow some files to prevent reading.
> Now, why unionfs is not enough is another question.
>
> I remember preparing a Fuse-Unionfs chroot because of its runtime
> configurability. I ended up with around 100 branches, though, and it had
> pitiful performance (tens of stats on file access are no good..).
>