linux/include/asm-x86/page.h
Arjan van de Ven ae531c26c5 x86: introduce /dev/mem restrictions with a config option
This patch introduces a restriction on /dev/mem: Only non-memory can be
read or written unless the newly introduced config option is set.

The X server needs access to /dev/mem for the PCI space, but it doesn't need
access to memory; both the file permissions and SELinux permissions of /dev/mem
just make X effectively super-super powerful. With the exception of the
BIOS area, there's just no valid app that uses /dev/mem on actual memory.
Other popular users of /dev/mem are rootkits and the like.
(note: mmap access of memory via /dev/mem was already not allowed since
a really long time)

People who want to use /dev/mem for kernel debugging can enable the config
option.

The restrictions of this patch have been in the Fedora and RHEL kernels for
at least 4 years without any problems.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-04-24 23:40:47 +02:00

185 lines
4.3 KiB
C

#ifndef _ASM_X86_PAGE_H
#define _ASM_X86_PAGE_H
#include <linux/const.h>
/* PAGE_SHIFT determines the page size */
#define PAGE_SHIFT 12
#define PAGE_SIZE (_AC(1,UL) << PAGE_SHIFT)
#define PAGE_MASK (~(PAGE_SIZE-1))
#ifdef __KERNEL__
#define PHYSICAL_PAGE_MASK (PAGE_MASK & __PHYSICAL_MASK)
#define PTE_MASK (_AT(long, PHYSICAL_PAGE_MASK))
#define PMD_PAGE_SIZE (_AC(1, UL) << PMD_SHIFT)
#define PMD_PAGE_MASK (~(PMD_PAGE_SIZE-1))
#define HPAGE_SHIFT PMD_SHIFT
#define HPAGE_SIZE (_AC(1,UL) << HPAGE_SHIFT)
#define HPAGE_MASK (~(HPAGE_SIZE - 1))
#define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT)
/* to align the pointer to the (next) page boundary */
#define PAGE_ALIGN(addr) (((addr)+PAGE_SIZE-1)&PAGE_MASK)
#define __PHYSICAL_MASK _AT(phys_addr_t, (_AC(1,ULL) << __PHYSICAL_MASK_SHIFT) - 1)
#define __VIRTUAL_MASK ((_AC(1,UL) << __VIRTUAL_MASK_SHIFT) - 1)
#ifndef __ASSEMBLY__
#include <linux/types.h>
#endif
#ifdef CONFIG_X86_64
#include <asm/page_64.h>
#else
#include <asm/page_32.h>
#endif /* CONFIG_X86_64 */
#define PAGE_OFFSET ((unsigned long)__PAGE_OFFSET)
#define VM_DATA_DEFAULT_FLAGS \
(((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0 ) | \
VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
#ifndef __ASSEMBLY__
extern int page_is_ram(unsigned long pagenr);
extern int devmem_is_allowed(unsigned long pagenr);
extern unsigned long max_pfn_mapped;
struct page;
static inline void clear_user_page(void *page, unsigned long vaddr,
struct page *pg)
{
clear_page(page);
}
static inline void copy_user_page(void *to, void *from, unsigned long vaddr,
struct page *topage)
{
copy_page(to, from);
}
#define __alloc_zeroed_user_highpage(movableflags, vma, vaddr) \
alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr)
#define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
typedef struct { pgdval_t pgd; } pgd_t;
typedef struct { pgprotval_t pgprot; } pgprot_t;
static inline pgd_t native_make_pgd(pgdval_t val)
{
return (pgd_t) { val };
}
static inline pgdval_t native_pgd_val(pgd_t pgd)
{
return pgd.pgd;
}
#if PAGETABLE_LEVELS >= 3
#if PAGETABLE_LEVELS == 4
typedef struct { pudval_t pud; } pud_t;
static inline pud_t native_make_pud(pmdval_t val)
{
return (pud_t) { val };
}
static inline pudval_t native_pud_val(pud_t pud)
{
return pud.pud;
}
#else /* PAGETABLE_LEVELS == 3 */
#include <asm-generic/pgtable-nopud.h>
static inline pudval_t native_pud_val(pud_t pud)
{
return native_pgd_val(pud.pgd);
}
#endif /* PAGETABLE_LEVELS == 4 */
typedef struct { pmdval_t pmd; } pmd_t;
static inline pmd_t native_make_pmd(pmdval_t val)
{
return (pmd_t) { val };
}
static inline pmdval_t native_pmd_val(pmd_t pmd)
{
return pmd.pmd;
}
#else /* PAGETABLE_LEVELS == 2 */
#include <asm-generic/pgtable-nopmd.h>
static inline pmdval_t native_pmd_val(pmd_t pmd)
{
return native_pgd_val(pmd.pud.pgd);
}
#endif /* PAGETABLE_LEVELS >= 3 */
static inline pte_t native_make_pte(pteval_t val)
{
return (pte_t) { .pte = val };
}
static inline pteval_t native_pte_val(pte_t pte)
{
return pte.pte;
}
#define pgprot_val(x) ((x).pgprot)
#define __pgprot(x) ((pgprot_t) { (x) } )
#ifdef CONFIG_PARAVIRT
#include <asm/paravirt.h>
#else /* !CONFIG_PARAVIRT */
#define pgd_val(x) native_pgd_val(x)
#define __pgd(x) native_make_pgd(x)
#ifndef __PAGETABLE_PUD_FOLDED
#define pud_val(x) native_pud_val(x)
#define __pud(x) native_make_pud(x)
#endif
#ifndef __PAGETABLE_PMD_FOLDED
#define pmd_val(x) native_pmd_val(x)
#define __pmd(x) native_make_pmd(x)
#endif
#define pte_val(x) native_pte_val(x)
#define __pte(x) native_make_pte(x)
#endif /* CONFIG_PARAVIRT */
#define __pa(x) __phys_addr((unsigned long)(x))
/* __pa_symbol should be used for C visible symbols.
This seems to be the official gcc blessed way to do such arithmetic. */
#define __pa_symbol(x) __pa(__phys_reloc_hide((unsigned long)(x)))
#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET))
#define __boot_va(x) __va(x)
#define __boot_pa(x) __pa(x)
#define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
#define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
#endif /* __ASSEMBLY__ */
#include <asm-generic/memory_model.h>
#include <asm-generic/page.h>
#define __HAVE_ARCH_GATE_AREA 1
#endif /* __KERNEL__ */
#endif /* _ASM_X86_PAGE_H */