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X-HELO: calimero.vinschen.de
Date: Thu, 9 Oct 2014 12:03:17 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Cannot exec() program outside of /bin if PATH is unset
Message-ID: <20141009100317.GI29235@calimero.vinschen.de>
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On Oct  8 19:15, Christian Franke wrote:
> Corinna Vinschen wrote:
> >On Sep 15 16:35, Christian Franke wrote:
> >>...
> >I'm somewhat reluctant to add a call to SetDllDirectory to the Cygwin
> >DLL for two reasons.
> >
> >- Calling SetDllDirectory with an explicit dir doesn't just add this dir
> >   to the search path, it also removes the CWD from the search path.
> >   While I agree that this is a good thing from a security POV, can we be
> >   sure that this behaviour isn't needed somewhere, by somebody?
> >
> >- The fact that SetDllDirectory affects searching linked DLLs in calls
> >   to CreateProcess is undocumented.  Per the original MSDN pages,
> >   SetDllDirectory affects calls to LoadLibrary and LoadLibraryEx, but
> >   not linked DLLs when starting a child process.  The latter is only
> >   mentioned in a Community Addition:
> >
> >   http://msdn.microsoft.com/en-us/library/windows/desktop/ms686203%28v=
=3Dvs.85%29.aspx
> >
> >Having said that, we can certainly test this, but I'm wondering
> >if an upstream Cygwin patch might be ok.  Something similar has been
> >applied to the portable OpenSSH repository years ago, so there's
> >precedent.
>=20
> We could leave this open for now. I already added an easy workaround to
> postfix
> (add PATH=3D/usr/bin to import/export_environment default settings).

Ok.  Or... hmm.  The fact that using SetDllDirectory disallows searching
the CWD got me thinking twice.  Security-wise it would really be the
right thing to do.  Usually DLLs are in defined search paths:

- Application dir
- Application defined dirs
- System dirs

So, what scenario would actually break by removing CWD from the search
path?  Running tests in an libtoolized project dir, perhaps?  Is that a
valid concern or did libtool already take care of this?


Corinna

--=20
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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