[PATCH 0/4] arm64: mmu: avoid writeable-executable mappings

[Laura Abbott]

On 02/10/2017 09:16 AM, Ard Biesheuvel wrote:
> Having memory that is writable and executable at the same time is a
> security hazard, and so we tend to avoid those when we can. However,
> at boot time, we keep .text mapped writable during the entire init
> phase, and the init region itself is mapped rwx as well.
> 
> Let's improve the situation by:
> - making the alternatives patching use the linear mapping
> - splitting the init region into separate text and data regions
> 
> This removes all RWX mappings except the really early one created
> in head.S (which we could perhaps fix in the future as well)
> 
> Ard Biesheuvel (4):
>   arm: kvm: move kvm_vgic_global_state out of .text section
>   arm64: alternatives: apply boot time fixups via the linear mapping
>   arm64: mmu: map .text as read-only from the outset
>   arm64: mmu: apply strict permissions to .init.text and .init.data
> 
>  arch/arm64/include/asm/mmu.h      |  1 +
>  arch/arm64/include/asm/sections.h |  3 +-
>  arch/arm64/kernel/alternative.c   |  6 +--
>  arch/arm64/kernel/smp.c           |  1 +
>  arch/arm64/kernel/vmlinux.lds.S   | 32 ++++++++++-----
>  arch/arm64/mm/init.c              |  3 +-
>  arch/arm64/mm/mmu.c               | 42 ++++++++++++++------
>  virt/kvm/arm/vgic/vgic.c          |  4 +-
>  8 files changed, 64 insertions(+), 28 deletions(-)
> 

Reviewed-by: Laura Abbott <labbott at redhat.com>