[patch 107/128] mm: enforce that vmap can't map pages executable

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From: Christoph Hellwig <hch@xxxxxx>
Subject: mm: enforce that vmap can't map pages executable

To help enforcing the W^X protection don't allow remapping existing pages
as executable.

x86 bits from Peter Zijlstra, arm64 bits from Mark Rutland.

Link: http://lkml.kernel.org/r/20200414131348.444715-20-hch@xxxxxx
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>.
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Gao Xiang <xiang@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>
Cc: Laura Abbott <labbott@xxxxxxxxxx>
Cc: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Cc: Robin Murphy <robin.murphy@xxxxxxx>
Cc: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
Cc: Wei Liu <wei.liu@xxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 arch/arm64/include/asm/pgtable.h     |    3 +++
 arch/x86/include/asm/pgtable_types.h |    6 ++++++
 include/asm-generic/pgtable.h        |    4 ++++
 mm/vmalloc.c                         |    2 +-
 4 files changed, 14 insertions(+), 1 deletion(-)

--- a/arch/arm64/include/asm/pgtable.h~mm-enforce-that-vmap-cant-map-pages-executable
+++ a/arch/arm64/include/asm/pgtable.h
@@ -407,6 +407,9 @@ static inline pmd_t pmd_mkdevmap(pmd_t p
 #define __pgprot_modify(prot,mask,bits) \
 	__pgprot((pgprot_val(prot) & ~(mask)) | (bits))
 
+#define pgprot_nx(prot) \
+	__pgprot_modify(prot, 0, PTE_PXN)
+
 /*
  * Mark the prot value as uncacheable and unbufferable.
  */
--- a/arch/x86/include/asm/pgtable_types.h~mm-enforce-that-vmap-cant-map-pages-executable
+++ a/arch/x86/include/asm/pgtable_types.h
@@ -282,6 +282,12 @@ typedef struct pgprot { pgprotval_t pgpr
 
 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
 
 /*
--- a/include/asm-generic/pgtable.h~mm-enforce-that-vmap-cant-map-pages-executable
+++ a/include/asm-generic/pgtable.h
@@ -491,6 +491,10 @@ static inline int arch_unmap_one(struct
 #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
--- a/mm/vmalloc.c~mm-enforce-that-vmap-cant-map-pages-executable
+++ a/mm/vmalloc.c
@@ -2391,7 +2391,7 @@ void *vmap(struct page **pages, unsigned
 	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;
_




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