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authorRussell King <rmk+kernel@arm.linux.org.uk>2013-07-31 20:58:56 (GMT)
committerRussell King <rmk+kernel@arm.linux.org.uk>2013-08-01 13:31:58 (GMT)
commita5463cd3435475386cbbe7b06e01292ac169d36f (patch)
tree71a32103b6df2be4fac877c60cdda2d9fe46e3a5
parent48be69a026b2c17350a5ef18a1959a919f60be7d (diff)
downloadlinux-a5463cd3435475386cbbe7b06e01292ac169d36f.tar.xz
ARM: make vectors page inaccessible from userspace
If kuser helpers are not provided by the kernel, disable user access to the vectors page. With the kuser helpers gone, there is no reason for this page to be visible to userspace. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r--arch/arm/include/asm/page.h2
-rw-r--r--arch/arm/kernel/process.c7
-rw-r--r--arch/arm/mm/mmu.c4
3 files changed, 12 insertions, 1 deletions
diff --git a/arch/arm/include/asm/page.h b/arch/arm/include/asm/page.h
index 6363f3d..4355f0e 100644
--- a/arch/arm/include/asm/page.h
+++ b/arch/arm/include/asm/page.h
@@ -142,7 +142,9 @@ extern void __cpu_copy_user_highpage(struct page *to, struct page *from,
#define clear_page(page) memset((void *)(page), 0, PAGE_SIZE)
extern void copy_page(void *to, const void *from);
+#ifdef CONFIG_KUSER_HELPERS
#define __HAVE_ARCH_GATE_AREA 1
+#endif
#ifdef CONFIG_ARM_LPAE
#include <asm/pgtable-3level-types.h>
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 566d0d7..1e6c33d 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -426,6 +426,7 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
}
#ifdef CONFIG_MMU
+#ifdef CONFIG_KUSER_HELPERS
/*
* The vectors page is always readable from user space for the
* atomic helpers. Insert it into the gate_vma so that it is visible
@@ -458,10 +459,14 @@ int in_gate_area_no_mm(unsigned long addr)
{
return in_gate_area(NULL, addr);
}
+#define is_gate_vma(vma) ((vma) = &gate_vma)
+#else
+#define is_gate_vma(vma) 0
+#endif
const char *arch_vma_name(struct vm_area_struct *vma)
{
- return (vma == &gate_vma) ? "[vectors]" :
+ return is_gate_vma(vma) ? "[vectors]" :
(vma->vm_mm && vma->vm_start == vma->vm_mm->context.sigpage) ?
"[sigpage]" : NULL;
}
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 9ea274d..ca46f41 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -1205,7 +1205,11 @@ static void __init devicemaps_init(struct machine_desc *mdesc)
map.pfn = __phys_to_pfn(virt_to_phys(vectors));
map.virtual = 0xffff0000;
map.length = PAGE_SIZE;
+#ifdef CONFIG_KUSER_HELPERS
map.type = MT_HIGH_VECTORS;
+#else
+ map.type = MT_LOW_VECTORS;
+#endif
create_mapping(&map);
if (!vectors_high()) {