On Wed, Apr 08, 2020 at 01:59:16PM +0200, Christoph Hellwig wrote:
> To help enforcing the W^X protection don't allow remapping existing
> pages as executable.
>
> Based on patch from Peter Zijlstra <peterz@xxxxxxxxxxxxx>.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> arch/x86/include/asm/pgtable_types.h | 6 ++++++
> include/asm-generic/pgtable.h | 4 ++++
> mm/vmalloc.c | 2 +-
> 3 files changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
> index 947867f112ea..2e7c442cc618 100644
> --- a/arch/x86/include/asm/pgtable_types.h
> +++ b/arch/x86/include/asm/pgtable_types.h
> @@ -282,6 +282,12 @@ typedef struct pgprot { pgprotval_t pgprot; } pgprot_t;
>
> typedef struct { pgdval_t pgd; } pgd_t;
>
> +static inline pgprot_t pgprot_nx(pgprot_t prot)
> +{
> + return __pgprot(pgprot_val(prot) | _PAGE_NX);
> +}
> +#define pgprot_nx pgprot_nx
> +
> #ifdef CONFIG_X86_PAE
I reckon for arm64 we can do similar in our <asm/pgtable.h>:
#define pgprot_nx(pgprot_t prot) \
__pgprot_modify(prot, 0, PTE_PXN)
... matching the style of our existing pgprot_*() modifier helpers.
Mark.
>
> /*
> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
> index 329b8c8ca703..8c5f9c29698b 100644
> --- a/include/asm-generic/pgtable.h
> +++ b/include/asm-generic/pgtable.h
> @@ -491,6 +491,10 @@ static inline int arch_unmap_one(struct mm_struct *mm,
> #define flush_tlb_fix_spurious_fault(vma, address) flush_tlb_page(vma, address)
> #endif
>
> +#ifndef pgprot_nx
> +#define pgprot_nx(prot) (prot)
> +#endif
> +
> #ifndef pgprot_noncached
> #define pgprot_noncached(prot) (prot)
> #endif
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 7356b3f07bd8..334c75251ddb 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -2390,7 +2390,7 @@ void *vmap(struct page **pages, unsigned int count,
> if (!area)
> return NULL;
>
> - if (map_kernel_range((unsigned long)area->addr, size, prot,
> + if (map_kernel_range((unsigned long)area->addr, size, pgprot_nx(prot),
> pages) < 0) {
> vunmap(area->addr);
> return NULL;
> --
> 2.25.1
>
