![Thomas Gleixner](/assets/img/avatar_default.png)
Based on 1 normalized pattern(s): 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 extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 1334 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Richard Fontana <rfontana@redhat.com> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
229 lines
5.5 KiB
C
229 lines
5.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/*
|
|
* flexible mmap layout support
|
|
*
|
|
* Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
|
|
* All Rights Reserved.
|
|
*
|
|
* 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(struct rlimit *rlim_stack)
|
|
{
|
|
if (current->personality & ADDR_COMPAT_LAYOUT)
|
|
return 1;
|
|
|
|
if (rlim_stack->rlim_cur == 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,
|
|
struct rlimit *rlim_stack)
|
|
{
|
|
unsigned long gap = rlim_stack->rlim_cur;
|
|
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;
|
|
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;
|
|
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,
|
|
struct rlimit *rlim_stack)
|
|
{
|
|
if (mmap_is_legacy(rlim_stack)) {
|
|
mm->mmap_base = TASK_UNMAPPED_BASE;
|
|
mm->get_unmapped_area = radix__arch_get_unmapped_area;
|
|
} else {
|
|
mm->mmap_base = mmap_base(random_factor, rlim_stack);
|
|
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,
|
|
struct rlimit *rlim_stack);
|
|
#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, struct rlimit *rlim_stack)
|
|
{
|
|
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,
|
|
rlim_stack);
|
|
/*
|
|
* Fall back to the standard layout if the personality
|
|
* bit is set, or if the expected stack growth is unlimited:
|
|
*/
|
|
if (mmap_is_legacy(rlim_stack)) {
|
|
mm->mmap_base = TASK_UNMAPPED_BASE;
|
|
mm->get_unmapped_area = arch_get_unmapped_area;
|
|
} else {
|
|
mm->mmap_base = mmap_base(random_factor, rlim_stack);
|
|
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
|
|
}
|
|
}
|