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Date: Fri, 26 Oct 2012 13:59:34 -0400 From: Mimi Zohar <zohar@...ux.vnet.ibm.com> To: Matthew Garrett <mjg@...hat.com> Cc: Vivek Goyal <vgoyal@...hat.com>, "Eric W. Biederman" <ebiederm@...ssion.com>, Khalid Aziz <khalid@...ehiking.org>, kexec@...ts.infradead.org, horms@...ge.net.au, Dave Young <dyoung@...hat.com>, "H. Peter Anvin" <hpa@...or.com>, linux kernel mailing list <linux-kernel@...r.kernel.org>, Dmitry Kasatkin <dmitry.kasatkin@...el.com>, Roberto Sassu <roberto.sassu@...ito.it>, Kees Cook <keescook@...omium.org> Subject: Re: Kdump with signed images On Fri, 2012-10-26 at 03:39 +0100, Matthew Garrett wrote: > On Thu, Oct 25, 2012 at 09:15:58PM -0400, Mimi Zohar wrote: > > > On a running system, the package installer, after verifying the package > > integrity, would install each file with the associated 'security.ima' > > extended attribute. The 'security.evm' digital signature would be > > installed with an HMAC, calculated using a system unique key. > > The idea isn't to prevent /sbin/kexec from being modified after > installation - it's to prevent it from being possible to install a > system that has a modified /sbin/kexec. Understood. > Leaving any part of this up to > the package installer means that it doesn't solve the problem we're > trying to solve here. It must be impossible for the kernel to launch any > /sbin/kexec that hasn't been signed by a trusted key that's been built > into the kernel, With Dmitry's patch "5e0d1a4 ima: added policy support for security.ima type", or something similar, we can force 'security.ima' to a specific type, in this case, a digital signature. With that patch, this shouldn't be a problem. > and it must be impossible for anything other than > /sbin/kexec to make the kexec system call. Permission is a MAC issue. :) thanks, Mimi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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