1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
/*
* Flexible mmap layout support
*
* Based on code by Ingo Molnar and Andi Kleen, copyrighted
* as follows:
*
* Copyright 2003-2009 Red Hat Inc.
* All Rights Reserved.
* Copyright 2005 Andi Kleen, SUSE Labs.
* Copyright 2007 Jiri Kosina, SUSE Labs.
*
* 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
*/
#include <linux/personality.h>
#include <linux/mm.h>
#include <linux/random.h>
#include <linux/limits.h>
#include <linux/sched/signal.h>
#include <linux/sched/mm.h>
#include <linux/compat.h>
#include <asm/elf.h>
struct va_alignment __read_mostly va_align = {
.flags = -1,
};
unsigned long tasksize_32bit(void)
{
return IA32_PAGE_OFFSET;
}
unsigned long tasksize_64bit(void)
{
return TASK_SIZE_MAX;
}
static unsigned long stack_maxrandom_size(unsigned long task_size)
{
unsigned long max = 0;
if ((current->flags & PF_RANDOMIZE) &&
!(current->personality & ADDR_NO_RANDOMIZE)) {
max = (-1UL) & __STACK_RND_MASK(task_size == tasksize_32bit());
max <<= PAGE_SHIFT;
}
return max;
}
#ifdef CONFIG_COMPAT
# define mmap32_rnd_bits mmap_rnd_compat_bits
# define mmap64_rnd_bits mmap_rnd_bits
#else
# define mmap32_rnd_bits mmap_rnd_bits
# define mmap64_rnd_bits mmap_rnd_bits
#endif
#define SIZE_128M (128 * 1024 * 1024UL)
static 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 arch_rnd(unsigned int rndbits)
{
return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
}
unsigned long arch_mmap_rnd(void)
{
if (!(current->flags & PF_RANDOMIZE))
return 0;
return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits);
}
static unsigned long mmap_base(unsigned long rnd, unsigned long task_size)
{
unsigned long gap = rlimit(RLIMIT_STACK);
unsigned long gap_min, gap_max;
/*
* Top of mmap area (just below the process stack).
* Leave an at least ~128 MB hole with possible stack randomization.
*/
gap_min = SIZE_128M + stack_maxrandom_size(task_size);
gap_max = (task_size / 6) * 5;
if (gap < gap_min)
gap = gap_min;
else if (gap > gap_max)
gap = gap_max;
return PAGE_ALIGN(task_size - gap - rnd);
}
static unsigned long mmap_legacy_base(unsigned long rnd,
unsigned long task_size)
{
return __TASK_UNMAPPED_BASE(task_size) + rnd;
}
/*
* This function, called very early during the creation of a new
* process VM image, sets up which VM layout function to use:
*/
static void arch_pick_mmap_base(unsigned long *base, unsigned long *legacy_base,
unsigned long random_factor, unsigned long task_size)
{
*legacy_base = mmap_legacy_base(random_factor, task_size);
if (mmap_is_legacy())
*base = *legacy_base;
else
*base = mmap_base(random_factor, task_size);
}
void arch_pick_mmap_layout(struct mm_struct *mm)
{
if (mmap_is_legacy())
mm->get_unmapped_area = arch_get_unmapped_area;
else
mm->get_unmapped_area = arch_get_unmapped_area_topdown;
arch_pick_mmap_base(&mm->mmap_base, &mm->mmap_legacy_base,
arch_rnd(mmap64_rnd_bits), tasksize_64bit());
#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
/*
* The mmap syscall mapping base decision depends solely on the
* syscall type (64-bit or compat). This applies for 64bit
* applications and 32bit applications. The 64bit syscall uses
* mmap_base, the compat syscall uses mmap_compat_base.
*/
arch_pick_mmap_base(&mm->mmap_compat_base, &mm->mmap_compat_legacy_base,
arch_rnd(mmap32_rnd_bits), tasksize_32bit());
#endif
}
unsigned long get_mmap_base(int is_legacy)
{
struct mm_struct *mm = current->mm;
#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
if (in_compat_syscall()) {
return is_legacy ? mm->mmap_compat_legacy_base
: mm->mmap_compat_base;
}
#endif
return is_legacy ? mm->mmap_legacy_base : mm->mmap_base;
}
const char *arch_vma_name(struct vm_area_struct *vma)
{
if (vma->vm_flags & VM_MPX)
return "[mpx]";
return NULL;
}
|
