On Thu, 2012-11-01 at 10:29 -0400, Eric Paris wrote: > On Thu, Nov 1, 2012 at 5:59 AM, James Bottomley > <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote: > > > But that doesn't really help me: untrusted root is an oxymoron. > > Imagine you run windows and you've never heard of Linux. You like > that only windows kernels can boot on your box and not those mean > nasty hacked up malware kernels. Now some attacker manages to take > over your box because you clicked on that executable for young models > in skimpy bathing suits. That executable rewrote your bootloader to > launch a very small carefully crafted Linux environment. This > environment does nothing but launch a perfectly valid signed Linux > kernel, which gets a Windows environment all ready to launch after > resume and goes to sleep. Now you have to hit the power button twice > every time you turn on your computer, weird, but Windows comes up, and > secureboot is still on, so you must be safe! So you're going back to the root exploit problem? I thought that was debunked a few emails ago in the thread? Your attack vector isn't plausible because for the suspend attack to work, the box actually has to be running Linux by default ... I think the admin of that box might notice if it suddenly started running windows ... > In this case we have a completely 'untrusted' root inside Linux. From > the user PoV root and Linux are both malware. Notice the EXACT same > attack would work launching rootkit'd Linux from Linux. So don't > pretend not to care about Windows. It's just that launching malware > Linux seems like a reason to get your key revoked. We don't want > signed code which can be used as an attack vector on ourselves or on > others. > > That make sense? Not really, no. A windows attack vector is a pointless abstraction because we're talking about securing Linux and your vector requires a Linux attack for the windows compromise ... let's try to keep on point to how we're using this feature to secure Linux. James -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
