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From Jeff Trawick <traw...@gmail.com>
Subject Re: svn commit: r773881 - in /httpd/httpd/branches/2.2.x: CHANGES STATUS include/http_core.h modules/filters/mod_include.c server/config.c server/core.c
Date Thu, 21 May 2009 18:39:57 GMT
On Wed, May 20, 2009 at 8:53 AM, Joe Orton <jorton@redhat.com> wrote:

> On Sun, May 17, 2009 at 11:15:00AM -0400, Jeff Trawick wrote:
> > On Tue, May 12, 2009 at 9:17 AM, <covener@apache.org> wrote:
> >
> > > Author: covener
> > > Date: Tue May 12 13:17:29 2009
> > > New Revision: 773881
> > >
> > > URL: http://svn.apache.org/viewvc?rev=773881&view=rev
> > > Log:
> > > backport 772997, 773322, 773342 from trunk.
> > > Reviewed By: jorton, rpluem, covener
> > >
> > > Security fix for CVE-2009-1195: fix Options handling such that
> > > 'AllowOverride Options=IncludesNoExec' does not permit Includes with
> > > exec= enabled to be configured in an .htaccess file:
> > >
> > > * include/http_core.h: Change semantics of Includes/IncludeNoExec
> > >  options bits to be additive; OPT_INCLUDES now means SSI is enabled
> > >  without exec=.  OPT_INCLUDES|OPT_INC_WITH_EXEC means SSI is enabled
> > >  with exec=.
> >
> >
> > Current mod_perl tarballs reference OPT_INC_WITH_EXEC as part of mapping
> the
> > httpd API into perl, and the mod_perl build fails because of this.
> >
> > ("modperl_config.c", line 525: undefined symbol: OPT_INCNOEXEC)
>
> Ick :( For some reason I thought this was hidden by CORE_PRIVATE, for
> what little that's worth.
>
> > While I don't understand why the mod_perl mappings are created at release
> > time against who knows what httpd, it brings up an interesting httpd
> issue
> > anyway.
> >
> > If some module does have OPT_INCNOEXEC baked in (32), it matches what
> > 2.2.12+ thinks is OPT_INC_WITH_EXEC.  Similarly, the old
> OPT_INC_WITH_EXEC
> > (previously called OPT_INCLUDES), maps what 2.2.12+ thinks is
> > OPT_INCLUDES-without-exec.
> >
> > We could swap the values of OPT_INCLUDES and OPT_INC_WITH_EXEC to lessen
> the
> > chance of some theoretical module making the wrong decision.
> >
> > We can also define OPT_INCNOEXEC to something (either the new
> OPT_INCLUDES
> > or "Get your mod_perl patch at XXX").
>
> Given that the semantics of the options has changed, I don't think it's
> worth changing httpd to maintain any pretence of compile-time or
> run-time compatibility here.  Any code using the OPT_* constants as
> exposed by mod_perl cannot work as expected any more.
>
> Regards, Joe
>

Is the change in semantics required to fix the bug, or is it simply the
current implementation?

As these constants and the related ap_allow_options() have been exposed to
the C API for eons, and passed through in API mappings such as mod_perl, it
is worth making an alternate fix to avoid breaking module compiles and
(potentially) module misbehavior when upgrading from 2.2.11 to 2.2.12.

Unfortunately I don't have a patch :(

Does somebody else care to share their opinion on this?  Which of these are
okay?

- existing mod_perl releases (and potentially other third-party modules)
won't compile with 2.2.12
- existing Perl modules (and potentially other third-party modules) will
confuse include-with-exec and include-without-exec

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