[RFC 0/3] extend kexec_file_load system call
vgoyal at redhat.com
Wed Jul 20 05:46:49 PDT 2016
On Wed, Jul 20, 2016 at 09:35:30AM +0100, Russell King - ARM Linux wrote:
> On Wed, Jul 20, 2016 at 01:45:42PM +1000, Balbir Singh wrote:
> > > IOW, if your kernel forced signature verification, you should not be
> > > able to do sig_enforce=0. If you kernel did not have
> > > CONFIG_MODULE_SIG_FORCE=y, then sig_enforce should be 0 by default anyway
> > > and you are not making it worse using command line.
> > OK.. I checked and you are right, but that is an example and there are
> > other things like security=, thermal.*, nosmep, nosmap that need auditing
> > for safety and might hurt the system security if used. I still think
> > think that assuming you can pass any command line without breaking security
> > is a broken argument.
> Quite, and you don't need to run code in a privileged environment to do
> any of that.
> It's also not trivial to protect against: new kernels gain new arguments
> which older kernels may not know about. No matter how much protection
> is built into older kernels, newer kernels can become vulnerable through
> the addition of further arguments.
If a new kernel command line option becomes an issue, new kernel can
block that in secureboot environment. That way it helps kexec
boot as well as regular boot.
More information about the kexec