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Date: Wed, 1 Oct 2014 15:32:28 +0200
From: Tomas Hoger <thoger@...hat.com>
To: oss-security@...ts.openwall.com
Subject: Re: Healing the bash fork
On Tue, 30 Sep 2014 19:19:55 -0400 (EDT) David A. Wheeler wrote:
> * Approach 1: Florian Weimer's approach. Bash functions to be
> exported have a prefix ("BASH_FUNC_") and suffix added. Then, ONLY
> environment variables with that prefix and suffix are interpreted
> specially. This approach is used by Red Hat, CentOS, Debian, Ubuntu,
> and Cygwin (at least), and was later accepted into bash upstream.
> The original approach used "()" as the suffix; bash upstream took
> this but switched to the "%%" suffix instead, which is a nice
> improvement (since "%" is not a shell metacharacter this is less
> likely to trigger OTHER problems). I know Cygwin is using the bash
> upstream '%%' suffix.
The following indicates there is other prefix and suffix used, that
makes these incompatibility issues worse:
http://support.apple.com/kb/HT6495
The names of all environment variables that introduce function
definitions are required to have a prefix "__BASH_FUNC<" and suffix
">()" to prevent unintended function passing via HTTP headers.
--
Tomas Hoger / Red Hat Product Security
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