linux/arch/s390/mm/mmap.c
Heiko Carstens 7aba842f08 s390/mmap: randomize mmap base for bottom up direction
Implement mmap base randomization for the bottom up direction, so ASLR
works for both mmap layouts on s390.  See also commit df54d6fa54 ("x86
get_unmapped_area(): use proper mmap base for bottom-up direction").

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Radu Caragea <sinaelgl@gmail.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-13 12:09:08 +09:00

181 lines
4.7 KiB
C

/*
* flexible mmap layout support
*
* Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*
* Started by Ingo Molnar <mingo@elte.hu>
*/
#include <linux/personality.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/compat.h>
#include <asm/pgalloc.h>
static unsigned long stack_maxrandom_size(void)
{
if (!(current->flags & PF_RANDOMIZE))
return 0;
if (current->personality & ADDR_NO_RANDOMIZE)
return 0;
return STACK_RND_MASK << PAGE_SHIFT;
}
/*
* Top of mmap area (just below the process stack).
*
* Leave at least a ~32 MB hole.
*/
#define MIN_GAP (32*1024*1024)
#define MAX_GAP (STACK_TOP/6*5)
static inline int mmap_is_legacy(void)
{
if (current->personality & ADDR_COMPAT_LAYOUT)
return 1;
if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
return 1;
return sysctl_legacy_va_layout;
}
static unsigned long mmap_rnd(void)
{
if (!(current->flags & PF_RANDOMIZE))
return 0;
/* 8MB randomization for mmap_base */
return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
}
static unsigned long mmap_base_legacy(void)
{
return TASK_UNMAPPED_BASE + mmap_rnd();
}
static inline unsigned long mmap_base(void)
{
unsigned long gap = rlimit(RLIMIT_STACK);
if (gap < MIN_GAP)
gap = MIN_GAP;
else if (gap > MAX_GAP)
gap = MAX_GAP;
gap &= PAGE_MASK;
return STACK_TOP - stack_maxrandom_size() - mmap_rnd() - gap;
}
#ifndef CONFIG_64BIT
/*
* This function, called very early during the creation of a new
* process VM image, sets up which VM layout function to use:
*/
void arch_pick_mmap_layout(struct mm_struct *mm)
{
/*
* Fall back to the standard layout if the personality
* bit is set, or if the expected stack growth is unlimited:
*/
if (mmap_is_legacy()) {
mm->mmap_base = mmap_base_legacy();
mm->get_unmapped_area = arch_get_unmapped_area;
} else {
mm->mmap_base = mmap_base();
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
}
}
#else
int s390_mmap_check(unsigned long addr, unsigned long len, unsigned long flags)
{
if (is_compat_task() || (TASK_SIZE >= (1UL << 53)))
return 0;
if (!(flags & MAP_FIXED))
addr = 0;
if ((addr + len) >= TASK_SIZE)
return crst_table_upgrade(current->mm, 1UL << 53);
return 0;
}
static unsigned long
s390_get_unmapped_area(struct file *filp, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct mm_struct *mm = current->mm;
unsigned long area;
int rc;
area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
if (!(area & ~PAGE_MASK))
return area;
if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
/* Upgrade the page table to 4 levels and retry. */
rc = crst_table_upgrade(mm, 1UL << 53);
if (rc)
return (unsigned long) rc;
area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
}
return area;
}
static unsigned long
s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
const unsigned long len, const unsigned long pgoff,
const unsigned long flags)
{
struct mm_struct *mm = current->mm;
unsigned long area;
int rc;
area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
if (!(area & ~PAGE_MASK))
return area;
if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < (1UL << 53)) {
/* Upgrade the page table to 4 levels and retry. */
rc = crst_table_upgrade(mm, 1UL << 53);
if (rc)
return (unsigned long) rc;
area = arch_get_unmapped_area_topdown(filp, addr, len,
pgoff, flags);
}
return area;
}
/*
* This function, called very early during the creation of a new
* process VM image, sets up which VM layout function to use:
*/
void arch_pick_mmap_layout(struct mm_struct *mm)
{
/*
* Fall back to the standard layout if the personality
* bit is set, or if the expected stack growth is unlimited:
*/
if (mmap_is_legacy()) {
mm->mmap_base = mmap_base_legacy();
mm->get_unmapped_area = s390_get_unmapped_area;
} else {
mm->mmap_base = mmap_base();
mm->get_unmapped_area = s390_get_unmapped_area_topdown;
}
}
#endif