Claimed Zero Day exploit in Samba.

Michael Gilbert michael.s.gilbert at
Fri Feb 5 14:10:00 MST 2010

On Fri, 5 Feb 2010 12:46:06 -0800, Jeremy Allison wrote:
> On Fri, Feb 05, 2010 at 03:48:37PM -0500, Michael Gilbert wrote:
> > 
> > in your original description, you stated that "wide links = no" will
> > generate an "access denied" error when a "wide link" is accessed;
> > however, you didn't mention that creation of "wide links" is also
> > prevented.  if this is true, then that is a very satisfactory
> > solution.
> No, it's actually incorrect. If "wide links = no", then no
> one can ever access anything off share, and so UNIX symlinks
> should be allowed to point to anywhere they like, as UNIX
> clients will follow them locally, not on the server.
> > however, i think that the prevention code itself already
> > solves the root of the issue, and enabling that by default would fully
> > solve the problem.
> Nope - see above :-).
> > i can understand giving the local administrator this capability.
> > however, i don't see the need for remote users to have such authority
> > (although any enlightenment would be very much appreciated).
> Imagine an app running on a Linux client that needs a symlink
> to /usr/local/lib inside it's filespace (don't know why, but
> it might :-). If that app is run off a CIFSFS share creating
> the /usr/local/lib symlink would fail with "wide links = no",
> which is not what you want.

that's a very good example.  would it be wrong to dictate that local
paths must be hardcoded, rather than symlinked (or manually symlinked
by the samba server administrator)?


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