oss-security - Re: Multiple libraries privilege checking

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Date: Thu, 19 May 2011 00:45:23 +0400
From: Solar Designer <solar@...nwall.com>
To: oss-security@...ts.openwall.com
Subject: Re: Multiple libraries privilege checking

On Tue, May 17, 2011 at 01:18:33PM +0200, Sebastian Krahmer wrote:
> I uploaded a openssl-1.0.0d patch to
> 
> http://suse.de/~krahmer/libs-vs-fscaps

Thank you!

> The prefered way is to check the dumpable flag via prctl() which
> is detected by the config script.

This is fail-open (at build time).  If the -e "/usr/include/sys/prctl.h"
check somehow fails, we silently get an insecure build.  Of course,
risks of this nature are extremely common, but we're trying to deal with
them.  In our package of rpm, we have the configure-presets script,
which looks like:

#!/bin/sh
# These autoconf variables are predefined to harden configure checks for
# security sensitive functions, and to speedup configure checks for
# most popular functions.
export ac_cv_func_alloca=yes
export ac_cv_func_asprintf=yes
export ac_cv_func_atexit=yes
export ac_cv_func_bcopy=yes
export ac_cv_func_dcgettext=yes
export ac_cv_func_fchdir=yes
...
export ac_cv_func_utimes=yes
export ac_cv_func_vasprintf=yes
export ac_cv_func_vfork=yes
export ac_cv_func_vprintf=yes
export ac_cv_func_vsnprintf=yes
export ac_cv_func_waitpid=yes
export ac_cv_func_wcslen=yes
export ac_cv_func_wcwidth=yes

This script is sourced in our %___build_pre macro.

Maybe you should simply drop the -e "/usr/include/sys/prctl.h" check,
leaving only the $target =~ /^linux/i check?

Thanks again,

Alexander

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