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Date: Tue, 17 May 2011 02:26:42 +0400
From: "Dmitry V. Levin" <>
Subject: Re: Multiple libraries privilege checking

On Mon, May 16, 2011 at 10:56:37PM +0400, Solar Designer wrote:
> On Mon, May 16, 2011 at 04:27:41PM +0200, Sebastian Krahmer wrote:
> > Its probably about time to review libraries that are commonly
> > linked to (formerly-) suid programs, such as
> > libldap, libssl etc. In near future, in the advent of file caps
> > they are often lacking proper checks.
> Good idea.
> > They usually just compare uid against euid (not even gid sometimes)
> > and do not check the dumpable flag or AT_SECURE (dont know whether
> > glibc exports a proper function to easily check that at all).
> glibc exports the __libc_enable_secure variable, which is initialized
> based on AT_* including AT_SECURE.  It also exports __secure_getenv().

There is a problem: in upstream glibc, __libc_enable_secure is placed into
GLIBC_PRIVATE section, thus making it unavailable in most of rpm-based
distros.  This is surely not the case in Owl and ALT Linux, where
__libc_enable_secure is legal interface for use in applications,
and some essential libraries are already patched to use
__libc_enable_secure instead of uid comparisons.


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