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@infradead.org.

Signed-off-by: Christoph Hellwig hch@lst.de

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