Date: Tue, 17 Nov 2015 10:34:46 -0700 From: Jeff Law <law@...hat.com> To: Solar Designer <solar@...nwall.com> Cc: Bernd Schmidt <bschmidt@...hat.com>, oss-security@...ts.openwall.com, Florian Weimer <fweimer@...hat.com> Subject: Re: Fwd: x86 ROP mitigation On 11/17/2015 09:24 AM, Bernd Schmidt wrote: > On 11/17/2015 04:39 PM, Solar Designer wrote: > > A few days ago, Bernd Schmidt posted this gcc patch: > > > > https://gcc.gnu.org/ml/gcc-patches/2015-11/msg01773.html > > > > "This adds a new -mmitigate-rop option to the i386 port. The idea is to > > mitigate against certain forms of attack called "return oriented > > programming" that some of our security folks are concerned about. > > [...] > > This patch is a small step towards preventing this kind of attack. > > I have a few more steps queued (not quite ready for stage 1), but > > additional work will be necessary to give reasonable protection." > > > > This was followed with a few tweets: > [...] > Obviously, I'm aware that this by itself isn't going to do very much. I > said so in my submission email! But you have to start somewhere, and > these pieces were ready. Right. It's a small piece of a much longer term effort to start spoiling ROP gadgets, both those which are inherent in the normal instruction stream (ie function epilogues) and those which are a result of the variable length instruction nature of the x86 ISA. > > > Bernd, I'd appreciate it if you describe your plan in a reply to this > > e-mail. Please keep oss-security CC'ed. > > I wouldn't call it my plan. I'm essentially in the role of implementing > requirements that others with more knowledge of the security issues come > up with. > > The plan, as far as it goes, is to start picking low-hanging fruit, and > hopefully build up over time until we have something that actually > provides protection. Things that we've discussed include: Right. I don't think anyone believes this stuff will make a significant difference *at this stage*. Thus, we aren't planning announcements or any promotion of the work. The obvious idea is to keep knocking off sources of ROP gadgets, hopefully reaching a point where ROP gadgets are reasonably hard to find & exploit in GCC generated code at some point in the future. As each bundle of work reaches completion, it will be submitted to the appropriate project (GCC & binutils). There's no value in holding back any particular mitigation technique. They'll just keep dropping as they're completed. FWIW, mod R/M is the only work that I see landing in GCC 6 given its development window closed earlier this week. If you have any questions, feel free to contact me directly. Jeff
Powered by blists - more mailing lists
Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.