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Re: [PATCH v2] libio: use PTR_MANGLE/PTR_DEMANGLE for FILE vtables
- From: Florian Weimer <fweimer at redhat dot com>
- To: Kees Cook <keescook at chromium dot org>, Joseph Myers <joseph at codesourcery dot com>, libc-alpha <libc-alpha at sourceware dot org>, Adam Conrad <adconrad at 0c3 dot net>
- Date: Sat, 3 Oct 2015 21:49:12 +0200
- Subject: Re: [PATCH v2] libio: use PTR_MANGLE/PTR_DEMANGLE for FILE vtables
- Authentication-results: sourceware.org; auth=none
- References: <20151001184048 dot GA31563 at www dot outflux dot net> <560D8108 dot 6060802 at redhat dot com> <alpine dot DEB dot 2 dot 10 dot 1510012059180 dot 9824 at digraph dot polyomino dot org dot uk> <CAGXu5jLbUeqy9+Q9KOVGaD=s_HQtz2bbyaFmNfcUf2n+9yqesQ at mail dot gmail dot com> <alpine dot DEB dot 2 dot 10 dot 1510012140380 dot 9824 at digraph dot polyomino dot org dot uk> <CAGXu5jJ9_a6L5OSw-0VZ76A+2pvSooT_1ysXvyzZYGQsATdznw at mail dot gmail dot com> <20151002222242 dot GA4308 at vapier dot lan>
On 10/03/2015 12:22 AM, Mike Frysinger wrote:
> On 01 Oct 2015 15:27, Kees Cook wrote:
>> Okay, so, since roughly 2007? Should I name the config "--only-v6+" or
It's more like 2003, but I need to double-check the dates.
> i wouldn't make it opaque. just call it something like "libio-file-ptr-mangle".
It should be --disable-libio-compatibility or something like that. If
we know all the possible vtables, we can do much better in terms of
hardening, and likely even devirtualize some of the function calls.
Pointer mangling is better than nothing, but I don't think the option
should be tied to that.
> then in the documentation, describe the possible limitations.
I plan to put the results of my libio archaeology on the wiki. It
should make documenting the impact of the new configure option easier.