Re: Memory Read Only Enforcement: VMM assisted kernel rootkit mitigation for KVM

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, Jul 19, 2018 at 11:37:59PM +0200, Ahmed Abd El Mawgood wrote:
> Hi,
> 
> This is my first set of patches that works as I would expect, and the
> third revision I sent to mailing lists.
> 
> Following up with my previous discussions about kernel rootkit mitigation
> via placing R/O protection on critical data structure, static data,
> privileged registers with static content. These patches present the
> first part where it is only possible to place these protections on
> memory pages. Feature-wise, this set of patches is incomplete in the sense of:
> - They still don't protect privileged registers
> - They don't protect guest TLB from malicious gva -> gpa page mappings.
> But they provide sketches for a basic working design. Note that I am totally
> noob and it took lots of time and effort to get to this point. So sorry in
> advance if I overlooked something.

This reminds me of Xen PV page model. That is the hypervisor is the one
auditing the page tables and the guest's pages are read-only.

Ditto for IDT, GDT, etc. Gosh, did you by chance look at how
Xen PV mechanism is done? It may provide the protection you are looking for?

CC-ing xen-devel.
> 
> [PATCH 1/3] [RFC V3] KVM: X86: Memory ROE documentation
> [PATCH 2/3] [RFC V3] KVM: X86: Adding arbitrary data pointer in kvm memslot itterator functions
> [PATCH 3/3] [RFC V3] KVM: X86: Adding skeleton for Memory ROE
> 
> Summery:
> 
>  Documentation/virtual/kvm/hypercalls.txt |  14 ++++
>  arch/x86/include/asm/kvm_host.h          |  11 ++-
>  arch/x86/kvm/Kconfig                     |   7 ++
>  arch/x86/kvm/mmu.c                       | 127 ++++++++++++++++++++++---------
>  arch/x86/kvm/x86.c                       |  82 +++++++++++++++++++-
>  include/linux/kvm_host.h                 |   3 +
>  include/uapi/linux/kvm_para.h            |   1 +
>  virt/kvm/kvm_main.c                      |  29 ++++++-
>  8 files changed, 232 insertions(+), 42 deletions(-)
>