You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
248 lines
6.3 KiB
248 lines
6.3 KiB
/*
|
|
* 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/random.h>
|
|
#include <linux/sched/signal.h>
|
|
#include <linux/sched/mm.h>
|
|
#include <linux/elf-randomize.h>
|
|
#include <linux/security.h>
|
|
#include <linux/mman.h>
|
|
|
|
/*
|
|
* Top of mmap area (just below the process stack).
|
|
*
|
|
* Leave at least a ~128 MB hole.
|
|
*/
|
|
#define MIN_GAP (128*1024*1024)
|
|
#define MAX_GAP (TASK_SIZE/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;
|
|
}
|
|
|
|
unsigned long arch_mmap_rnd(void)
|
|
{
|
|
unsigned long shift, rnd;
|
|
|
|
shift = mmap_rnd_bits;
|
|
#ifdef CONFIG_COMPAT
|
|
if (is_32bit_task())
|
|
shift = mmap_rnd_compat_bits;
|
|
#endif
|
|
rnd = get_random_long() % (1ul << shift);
|
|
|
|
return rnd << PAGE_SHIFT;
|
|
}
|
|
|
|
static inline unsigned long stack_maxrandom_size(void)
|
|
{
|
|
if (!(current->flags & PF_RANDOMIZE))
|
|
return 0;
|
|
|
|
/* 8MB for 32bit, 1GB for 64bit */
|
|
if (is_32bit_task())
|
|
return (1<<23);
|
|
else
|
|
return (1<<30);
|
|
}
|
|
|
|
static inline unsigned long mmap_base(unsigned long rnd)
|
|
{
|
|
unsigned long gap = rlimit(RLIMIT_STACK);
|
|
unsigned long pad = stack_maxrandom_size() + stack_guard_gap;
|
|
|
|
/* Values close to RLIM_INFINITY can overflow. */
|
|
if (gap + pad > gap)
|
|
gap += pad;
|
|
|
|
if (gap < MIN_GAP)
|
|
gap = MIN_GAP;
|
|
else if (gap > MAX_GAP)
|
|
gap = MAX_GAP;
|
|
|
|
return PAGE_ALIGN(DEFAULT_MAP_WINDOW - gap - rnd);
|
|
}
|
|
|
|
#ifdef CONFIG_PPC_RADIX_MMU
|
|
/*
|
|
* Same function as generic code used only for radix, because we don't need to overload
|
|
* the generic one. But we will have to duplicate, because hash select
|
|
* HAVE_ARCH_UNMAPPED_AREA
|
|
*/
|
|
static unsigned long
|
|
radix__arch_get_unmapped_area(struct file *filp, unsigned long addr,
|
|
unsigned long len, unsigned long pgoff,
|
|
unsigned long flags)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma;
|
|
int fixed = (flags & MAP_FIXED);
|
|
unsigned long high_limit;
|
|
struct vm_unmapped_area_info info;
|
|
|
|
high_limit = DEFAULT_MAP_WINDOW;
|
|
if (addr >= high_limit || (fixed && (addr + len > high_limit)))
|
|
high_limit = TASK_SIZE;
|
|
|
|
if (len > high_limit)
|
|
return -ENOMEM;
|
|
if (fixed) {
|
|
if (addr > high_limit - len)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
if (unlikely(addr > mm->context.addr_limit &&
|
|
mm->context.addr_limit != TASK_SIZE))
|
|
mm->context.addr_limit = TASK_SIZE;
|
|
|
|
if (fixed)
|
|
return addr;
|
|
|
|
if (addr) {
|
|
addr = PAGE_ALIGN(addr);
|
|
vma = find_vma(mm, addr);
|
|
if (high_limit - len >= addr && addr >= mmap_min_addr &&
|
|
(!vma || addr + len <= vm_start_gap(vma)))
|
|
return addr;
|
|
}
|
|
|
|
info.flags = 0;
|
|
info.length = len;
|
|
info.low_limit = mm->mmap_base;
|
|
info.high_limit = high_limit;
|
|
info.align_mask = 0;
|
|
|
|
return vm_unmapped_area(&info);
|
|
}
|
|
|
|
static unsigned long
|
|
radix__arch_get_unmapped_area_topdown(struct file *filp,
|
|
const unsigned long addr0,
|
|
const unsigned long len,
|
|
const unsigned long pgoff,
|
|
const unsigned long flags)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct mm_struct *mm = current->mm;
|
|
unsigned long addr = addr0;
|
|
int fixed = (flags & MAP_FIXED);
|
|
unsigned long high_limit;
|
|
struct vm_unmapped_area_info info;
|
|
|
|
high_limit = DEFAULT_MAP_WINDOW;
|
|
if (addr >= high_limit || (fixed && (addr + len > high_limit)))
|
|
high_limit = TASK_SIZE;
|
|
|
|
if (len > high_limit)
|
|
return -ENOMEM;
|
|
if (fixed) {
|
|
if (addr > high_limit - len)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
if (unlikely(addr > mm->context.addr_limit &&
|
|
mm->context.addr_limit != TASK_SIZE))
|
|
mm->context.addr_limit = TASK_SIZE;
|
|
|
|
if (fixed)
|
|
return addr;
|
|
|
|
if (addr) {
|
|
addr = PAGE_ALIGN(addr);
|
|
vma = find_vma(mm, addr);
|
|
if (high_limit - len >= addr && addr >= mmap_min_addr &&
|
|
(!vma || addr + len <= vm_start_gap(vma)))
|
|
return addr;
|
|
}
|
|
|
|
info.flags = VM_UNMAPPED_AREA_TOPDOWN;
|
|
info.length = len;
|
|
info.low_limit = max(PAGE_SIZE, mmap_min_addr);
|
|
info.high_limit = mm->mmap_base + (high_limit - DEFAULT_MAP_WINDOW);
|
|
info.align_mask = 0;
|
|
|
|
addr = vm_unmapped_area(&info);
|
|
if (!(addr & ~PAGE_MASK))
|
|
return addr;
|
|
VM_BUG_ON(addr != -ENOMEM);
|
|
|
|
/*
|
|
* A failed mmap() very likely causes application failure,
|
|
* so fall back to the bottom-up function here. This scenario
|
|
* can happen with large stack limits and large mmap()
|
|
* allocations.
|
|
*/
|
|
return radix__arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
|
|
}
|
|
|
|
static void radix__arch_pick_mmap_layout(struct mm_struct *mm,
|
|
unsigned long random_factor)
|
|
{
|
|
if (mmap_is_legacy()) {
|
|
mm->mmap_base = TASK_UNMAPPED_BASE;
|
|
mm->get_unmapped_area = radix__arch_get_unmapped_area;
|
|
} else {
|
|
mm->mmap_base = mmap_base(random_factor);
|
|
mm->get_unmapped_area = radix__arch_get_unmapped_area_topdown;
|
|
}
|
|
}
|
|
#else
|
|
/* dummy */
|
|
extern void radix__arch_pick_mmap_layout(struct mm_struct *mm,
|
|
unsigned long random_factor);
|
|
#endif
|
|
/*
|
|
* 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)
|
|
{
|
|
unsigned long random_factor = 0UL;
|
|
|
|
if (current->flags & PF_RANDOMIZE)
|
|
random_factor = arch_mmap_rnd();
|
|
|
|
if (radix_enabled())
|
|
return radix__arch_pick_mmap_layout(mm, random_factor);
|
|
/*
|
|
* 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 = TASK_UNMAPPED_BASE;
|
|
mm->get_unmapped_area = arch_get_unmapped_area;
|
|
} else {
|
|
mm->mmap_base = mmap_base(random_factor);
|
|
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
|
|
}
|
|
}
|
|
|