Date: Tue, 10 Mar 2015 12:15:49 -0500 From: Leif Pedersen <bilbo@hobbiton.org> To: "freebsd-security@freebsd.org" <freebsd-security@freebsd.org> Subject: Re: DRAM Rowhammer exploits Message-ID: <CAK-wPOjqJ7bWSJ-X6CkdjdABZsd7NBVHz0UoH312LRS=aMVHWw@mail.gmail.com> In-Reply-To: <54FE12CE.1000401@digiware.nl> References: <alpine.BSF.2.00.1503092248580.38285@woozle.rinet.ru> <54FE12CE.1000401@digiware.nl>
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I have a suggestion. As a simpler measure, would it be possible to implement a test at boot time to determine whether the system is vulnerable? I guess such a test would have to run in the kernel to get the particular memory mapping required. The result would naturally emit a kernel message, but it would be much easier to monitor for automatically if it also set a read-only sysctl. For sure at my company, I would add an alert for such a test on our most accessible systems. I could easily replace any affected hardware on our DMZ and edge networks if I can identify it easily. For that matter, some hardware may not need replacing if I diddle with the over-clocker's BIOS settings. Ongoing monitoring matters because I'd hate to have someone swap hardware or reset the BIOS in an emergency and not know they opened the vulnerability. If the hardware can be worked around, that's very helpful, but the proposals sound like they'd have fairly severe performance impacts and/or be impossible to guarantee for all hardware. On many of our systems, multi-user security is just not an issue, and for them I would choose performance over fixing this problem or replacing the hardware. Indeed, I would keep the hardware removed from sensitive systems to reuse in more protected environments. In any case, I would think that having a reliable test would be very helpful to most of this audience. Without it, I'm fumbling in the dark. Does anyone empathize with this? - Leif
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