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Commit 5a0fdfad authored by Catalin Marinas's avatar Catalin Marinas
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Revert "arm64: Introduce execute-only page access permissions" 



This reverts commit bc07c2c6.

While the aim is increased security for --x memory maps, it does not
protect against kernel level reads. Until SECCOMP is implemented for
arm64, revert this patch to avoid giving a false idea of execute-only
mappings.

Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent cf5c95db

arch/arm64/include/asm/pgtable.h

+5 −6
Original line number Diff line number Diff line
@@ -86,13 +86,12 @@ extern void __pgd_error(const char *file, int line, unsigned long val); 
#define PAGE_COPY_EXEC		__pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN)

#define PAGE_READONLY		__pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN)

#define PAGE_READONLY_EXEC	__pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN)

#define PAGE_EXECONLY		__pgprot(_PAGE_DEFAULT | PTE_NG | PTE_PXN)



#define __P000  PAGE_NONE

#define __P001  PAGE_READONLY

#define __P010  PAGE_COPY

#define __P011  PAGE_COPY

#define __P100  PAGE_EXECONLY

#define __P100  PAGE_READONLY_EXEC

#define __P101  PAGE_READONLY_EXEC

#define __P110  PAGE_COPY_EXEC

#define __P111  PAGE_COPY_EXEC
@@ -101,7 +100,7 @@ extern void __pgd_error(const char *file, int line, unsigned long val); 
#define __S001  PAGE_READONLY

#define __S010  PAGE_SHARED

#define __S011  PAGE_SHARED

#define __S100  PAGE_EXECONLY

#define __S100  PAGE_READONLY_EXEC

#define __S101  PAGE_READONLY_EXEC

#define __S110  PAGE_SHARED_EXEC

#define __S111  PAGE_SHARED_EXEC
@@ -137,8 +136,8 @@ extern struct page *empty_zero_page; 
#define pte_write(pte)		(!!(pte_val(pte) & PTE_WRITE))

#define pte_exec(pte)		(!(pte_val(pte) & PTE_UXN))



#define pte_valid_ng(pte) \

	((pte_val(pte) & (PTE_VALID | PTE_NG)) == (PTE_VALID | PTE_NG))

#define pte_valid_user(pte) \

	((pte_val(pte) & (PTE_VALID | PTE_USER)) == (PTE_VALID | PTE_USER))



static inline pte_t pte_wrprotect(pte_t pte)

{
@@ -192,7 +191,7 @@ extern void __sync_icache_dcache(pte_t pteval, unsigned long addr); 
static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,

			      pte_t *ptep, pte_t pte)

{

	if (pte_valid_ng(pte)) {

	if (pte_valid_user(pte)) {

		if (!pte_special(pte) && pte_exec(pte))

			__sync_icache_dcache(pte, addr);

		if (pte_dirty(pte) && pte_write(pte))

arch/arm64/mm/fault.c

+3 −2
Original line number Diff line number Diff line
@@ -173,7 +173,8 @@ static int __do_page_fault(struct mm_struct *mm, unsigned long addr, 
good_area:

	/*

	 * Check that the permissions on the VMA allow for the fault which

	 * occurred.

	 * occurred. If we encountered a write or exec fault, we must have

	 * appropriate permissions, otherwise we allow any permission.

	 */

	if (!(vma->vm_flags & vm_flags)) {

		fault = VM_FAULT_BADACCESS;
@@ -195,7 +196,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, 
	struct task_struct *tsk;

	struct mm_struct *mm;

	int fault, sig, code;

	unsigned long vm_flags = VM_READ | VM_WRITE;

	unsigned long vm_flags = VM_READ | VM_WRITE | VM_EXEC;

	unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;



	tsk = current;