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
