RFC: Cygwin 64 bit?

[Corinna Vinschen]

On Aug 18 09:58, Ryan Johnson wrote:
> On 18/08/2011 9:24 AM, Corinna Vinschen wrote:
> >On Aug 18 15:10, Peter Rosin wrote:
> >>Den 2011-08-18 11:20 skrev Corinna Vinschen:
> >>>So, nobody except Earnie is interested in the way dlopen opens shared
> >>>objects?  Nobody even replied to the idea of the pseudo algorithm below.
> >>>Does really nobody care?
> >>I have one little reservation, I don't like it when adding a seemingly
> >>unrelated file can break old stuff. For example, let's say that I in the
> >>future have an application that relies on the fact that it can dlopen
> >>"libfoo.so" and get "cygfoo.dll". Everything works fine. If I then
> >>install something that brings in a real "libfoo.so" things will break.
> >>It's even a security problem because a carefully crafted rouge
> >>libfoo.so can appear to work but do unwanted stuff behind my back.
> >That's a good point.  I don't know how critical that is.  Maybe it would
> >help to change the order, along these lines:
> >
> >   incoming: libfoo.so
> >   1. check: cygfoo.dll
> >   2. check: libfoo.dll
> >   3. check: libfoo.so
> >
> >But, of course, regardless of the order, there's always a chance to
> >slip something in.
> In theory it does sound bad, but I'm not sure how much of a hole it
> leaves in practice: the fact that the adversary has to resort to
> different names rather than simply replacing the targeted library
> means they have pretty limited control. They can't just
> delete/rename their target, nor can they stick a decoy earlier in
> [LD_LIBRARY_]PATH, so they have to resort to exploiting this name
> overloading. The only way around it that I can think of right off
> would be if some directory in the search path has the 't' permission
> set (like /tmp does), so they can add new files even though they
> can't mess with other files there. That seems unlikely (or at least,
> easily fixed).

I agree.

> More likely it just adds a new facet to the existing dll purgatory
> which poor unfortunate developers already have to navigate. Which,
> ironically, is usually resolved by putting everything you care about
> in the same directory as the executable (so maybe that's another
> reason to leave dlls in/bin).

Indeed.  Unless we don't create standard DLLs but a special kind of
shared object files which are not search using the default search path
anymore at all, because the loader is builtin into the Cygwin DLL
instead of relying on the Windows loader.  However feasible *that* is.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat