From 26ffd0d43b186b0d5186354da8714a1c2d360df0 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Sat, 1 Sep 2012 05:22:12 +0100 Subject: ARM: mm: introduce present, faulting entries for PAGE_NONE PROT_NONE mappings apply the page protection attributes defined by _P000 which translate to PAGE_NONE for ARM. These attributes specify an XN, RDONLY pte that is inaccessible to userspace. However, on kernels configured without support for domains, such a pte *is* accessible to the kernel and can be read via get_user, allowing tasks to read PROT_NONE pages via syscalls such as read/write over a pipe. This patch introduces a new software pte flag, L_PTE_NONE, that is set to identify faulting, present entries. Signed-off-by: Will Deacon --- arch/arm/include/asm/pgtable.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'arch/arm/include/asm/pgtable.h') diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h index ccf34b6e9903..9c82f988c0e3 100644 --- a/arch/arm/include/asm/pgtable.h +++ b/arch/arm/include/asm/pgtable.h @@ -73,7 +73,7 @@ extern pgprot_t pgprot_kernel; #define _MOD_PROT(p, b) __pgprot(pgprot_val(p) | (b)) -#define PAGE_NONE _MOD_PROT(pgprot_user, L_PTE_XN | L_PTE_RDONLY) +#define PAGE_NONE _MOD_PROT(pgprot_user, L_PTE_XN | L_PTE_RDONLY | L_PTE_NONE) #define PAGE_SHARED _MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_XN) #define PAGE_SHARED_EXEC _MOD_PROT(pgprot_user, L_PTE_USER) #define PAGE_COPY _MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_RDONLY | L_PTE_XN) @@ -83,7 +83,7 @@ extern pgprot_t pgprot_kernel; #define PAGE_KERNEL _MOD_PROT(pgprot_kernel, L_PTE_XN) #define PAGE_KERNEL_EXEC pgprot_kernel -#define __PAGE_NONE __pgprot(_L_PTE_DEFAULT | L_PTE_RDONLY | L_PTE_XN) +#define __PAGE_NONE __pgprot(_L_PTE_DEFAULT | L_PTE_RDONLY | L_PTE_XN | L_PTE_NONE) #define __PAGE_SHARED __pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_XN) #define __PAGE_SHARED_EXEC __pgprot(_L_PTE_DEFAULT | L_PTE_USER) #define __PAGE_COPY __pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_RDONLY | L_PTE_XN) @@ -240,7 +240,7 @@ static inline pte_t pte_mkspecial(pte_t pte) { return pte; } static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) { - const pteval_t mask = L_PTE_XN | L_PTE_RDONLY | L_PTE_USER; + const pteval_t mask = L_PTE_XN | L_PTE_RDONLY | L_PTE_USER | L_PTE_NONE; pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask); return pte; } -- cgit v1.2.3