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Date: Fri, 20 Feb 2015 08:44:28 -0800
From: Paul Pluzhnikov <ppluzhnikov@...gle.com>
To: oss-security@...ts.openwall.com
Subject: Re: Fixing the glibc runtime linker
On Fri, Feb 20, 2015 at 1:22 AM, <Casper.Dik@...cle.com> wrote:
>
>>FWIW, relative RPATHs are quite fundamental to our test execution
>>environment, and any patch that unconditionally ignores them would
>>have to be reverted in our tree.
It turns out I was mistaken: we don't use relative RPATHs after all.
> But wouldn't that make the libraries and executables less reliable?
Our testing infrastructure is described in some detail here:
http://google-engtools.blogspot.com/2011/06/testing-at-speed-and-scale-of-google.html
The essential problem is that the paths to all the libraries in the cloud
are effectively unpredictable. They are however predictable relative to
$ORIGIN, which is what we actually use [1].
> They can pick up random libraries or cause some delays when one of the
> relative paths points to a NFS mounted directory.
We only build tests that way, not final binaries. Random libraries and
NFS are not a concern for us, because the 'in the cloud' environment is
tightly controlled -- we know exactly what files the test will see at
runtime (relative to $ORIGIN).
> Any reason you can't change to using LD_LIBRARY_PATH for testing?
We used to use LD_LIBRARY_PATH, but it has several problems. Consider a
Python or Java program that needs to load some C++ shared library, and
also wants to fork off a separate C++ executable. Consider further that
the python may be built for ix86, while the C++ executable may be built
for x86_64.
What should the LD_LIBRARY_PATH look like? Should it leak from python into
C++ executable? It's complicated :-)
[1] This isn't strictly true either, for complicated reasons irrelevant
to current discussion.
--
Paul Pluzhnikov
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