- introduce pte_exec_kern() to simplify the NX logic - split the definitions out of pgtable-[23]level.h into pgtable-[23]level-defs.h, to enable the former to use generic pte functions from pgtable.h. Signed-off-by: Ingo Molnar --- linux/arch/i386/mm/fault.c +++ linux/arch/i386/mm/fault.c @@ -436,8 +436,14 @@ no_context: bust_spinlocks(1); - if (nx_enabled && (error_code & 16)) - printk(KERN_CRIT "kernel tried to execute NX-protected page - exploit attempt? (uid: %d)\n", current->uid); +#ifdef CONFIG_X86_PAE + if (error_code & 16) { + pte_t *pte = lookup_address(address); + + if (pte && pte_present(*pte) && !pte_exec_kernel(*pte)) + printk(KERN_CRIT "kernel tried to execute NX-protected page - exploit attempt? (uid: %d)\n", current->uid); + } +#endif if (address < PAGE_SIZE) printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference"); else --- linux/arch/i386/mm/init.c +++ linux/arch/i386/mm/init.c @@ -470,7 +470,7 @@ int __init set_kernel_exec(unsigned long pte = lookup_address(vaddr); BUG_ON(!pte); - if (pte_val(*pte) & _PAGE_NX) + if (!pte_exec_kernel(*pte)) ret = 0; if (enable) --- linux/include/asm-i386/pgtable-2level-defs.h +++ linux/include/asm-i386/pgtable-2level-defs.h @@ -0,0 +1,20 @@ +#ifndef _I386_PGTABLE_2LEVEL_DEFS_H +#define _I386_PGTABLE_2LEVEL_DEFS_H + +/* + * traditional i386 two-level paging structure: + */ + +#define PGDIR_SHIFT 22 +#define PTRS_PER_PGD 1024 + +/* + * the i386 is two-level, so we don't really have any + * PMD directory physically. + */ +#define PMD_SHIFT 22 +#define PTRS_PER_PMD 1 + +#define PTRS_PER_PTE 1024 + +#endif /* _I386_PGTABLE_2LEVEL_DEFS_H */ --- linux/include/asm-i386/pgtable-2level.h +++ linux/include/asm-i386/pgtable-2level.h @@ -1,22 +1,6 @@ #ifndef _I386_PGTABLE_2LEVEL_H #define _I386_PGTABLE_2LEVEL_H -/* - * traditional i386 two-level paging structure: - */ - -#define PGDIR_SHIFT 22 -#define PTRS_PER_PGD 1024 - -/* - * the i386 is two-level, so we don't really have any - * PMD directory physically. - */ -#define PMD_SHIFT 22 -#define PTRS_PER_PMD 1 - -#define PTRS_PER_PTE 1024 - #define pte_ERROR(e) \ printk("%s:%d: bad pte %08lx.\n", __FILE__, __LINE__, (e).pte_low) #define pmd_ERROR(e) \ @@ -64,6 +48,22 @@ static inline pmd_t * pmd_offset(pgd_t * #define pfn_pmd(pfn, prot) __pmd(((pfn) << PAGE_SHIFT) | pgprot_val(prot)) /* + * All present user pages are user-executable: + */ +static inline int pte_exec(pte_t pte) +{ + return pte_user(pte); +} + +/* + * All present pages are kernel-executable: + */ +static inline int pte_exec_kernel(pte_t pte) +{ + return 1; +} + +/* * Bits 0, 6 and 7 are taken, split up the 29 bits of offset * into this range: */ --- linux/include/asm-i386/pgtable-3level-defs.h +++ linux/include/asm-i386/pgtable-3level-defs.h @@ -0,0 +1,22 @@ +#ifndef _I386_PGTABLE_3LEVEL_DEFS_H +#define _I386_PGTABLE_3LEVEL_DEFS_H + +/* + * PGDIR_SHIFT determines what a top-level page table entry can map + */ +#define PGDIR_SHIFT 30 +#define PTRS_PER_PGD 4 + +/* + * PMD_SHIFT determines the size of the area a middle-level + * page table can map + */ +#define PMD_SHIFT 21 +#define PTRS_PER_PMD 512 + +/* + * entries per page directory level + */ +#define PTRS_PER_PTE 512 + +#endif /* _I386_PGTABLE_3LEVEL_DEFS_H */ --- linux/include/asm-i386/pgtable-3level.h +++ linux/include/asm-i386/pgtable-3level.h @@ -8,24 +8,6 @@ * Copyright (C) 1999 Ingo Molnar */ -/* - * PGDIR_SHIFT determines what a top-level page table entry can map - */ -#define PGDIR_SHIFT 30 -#define PTRS_PER_PGD 4 - -/* - * PMD_SHIFT determines the size of the area a middle-level - * page table can map - */ -#define PMD_SHIFT 21 -#define PTRS_PER_PMD 512 - -/* - * entries per page directory level - */ -#define PTRS_PER_PTE 512 - #define pte_ERROR(e) \ printk("%s:%d: bad pte %p(%08lx%08lx).\n", __FILE__, __LINE__, &(e), (e).pte_high, (e).pte_low) #define pmd_ERROR(e) \ @@ -37,6 +19,29 @@ static inline int pgd_none(pgd_t pgd) { static inline int pgd_bad(pgd_t pgd) { return 0; } static inline int pgd_present(pgd_t pgd) { return 1; } +/* + * Is the pte executable? + */ +static inline int pte_x(pte_t pte) +{ + return !(pte_val(pte) & _PAGE_NX); +} + +/* + * All present user-pages with !NX bit are user-executable: + */ +static inline int pte_exec(pte_t pte) +{ + return pte_user(pte) && pte_x(pte); +} +/* + * All present pages with !NX bit are kernel-executable: + */ +static inline int pte_exec_kernel(pte_t pte) +{ + return pte_x(pte); +} + /* Rules for using set_pte: the pte being assigned *must* be * either not present or in a state where the hardware will * not attempt to update the pte. In places where this is --- linux/include/asm-i386/pgtable.h +++ linux/include/asm-i386/pgtable.h @@ -43,19 +43,15 @@ void pgd_dtor(void *, kmem_cache_t *, un void pgtable_cache_init(void); void paging_init(void); -#endif /* !__ASSEMBLY__ */ - /* * The Linux x86 paging architecture is 'compile-time dual-mode', it * implements both the traditional 2-level x86 page tables and the * newer 3-level PAE-mode page tables. */ -#ifndef __ASSEMBLY__ #ifdef CONFIG_X86_PAE -# include +# include #else -# include -#endif +# include #endif #define PMD_SIZE (1UL << PMD_SHIFT) @@ -73,8 +69,6 @@ void paging_init(void); #define BOOT_USER_PGD_PTRS (__PAGE_OFFSET >> TWOLEVEL_PGDIR_SHIFT) #define BOOT_KERNEL_PGD_PTRS (1024-BOOT_USER_PGD_PTRS) - -#ifndef __ASSEMBLY__ /* Just any arbitrary offset to the start of the vmalloc VM area: the * current 8MB value just means that there will be a 8MB "hole" after the * physical memory until the kernel virtual memory starts. That means that @@ -223,7 +217,6 @@ extern unsigned long pg0[]; */ static inline int pte_user(pte_t pte) { return (pte).pte_low & _PAGE_USER; } static inline int pte_read(pte_t pte) { return (pte).pte_low & _PAGE_USER; } -static inline int pte_exec(pte_t pte) { return (pte).pte_low & _PAGE_USER; } static inline int pte_dirty(pte_t pte) { return (pte).pte_low & _PAGE_DIRTY; } static inline int pte_young(pte_t pte) { return (pte).pte_low & _PAGE_ACCESSED; } static inline int pte_write(pte_t pte) { return (pte).pte_low & _PAGE_RW; } @@ -244,6 +237,12 @@ static inline pte_t pte_mkdirty(pte_t pt static inline pte_t pte_mkyoung(pte_t pte) { (pte).pte_low |= _PAGE_ACCESSED; return pte; } static inline pte_t pte_mkwrite(pte_t pte) { (pte).pte_low |= _PAGE_RW; return pte; } +#ifdef CONFIG_X86_PAE +# include +#else +# include +#endif + static inline int ptep_test_and_clear_dirty(pte_t *ptep) { if (!pte_dirty(*ptep))