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Commit | Line | Data |
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cc503c1b | 1 | /* |
675a0813 | 2 | * Flexible mmap layout support |
cc503c1b JK |
3 | * |
4 | * Based on code by Ingo Molnar and Andi Kleen, copyrighted | |
5 | * as follows: | |
6 | * | |
8f47e163 | 7 | * Copyright 2003-2009 Red Hat Inc. |
cc503c1b JK |
8 | * All Rights Reserved. |
9 | * Copyright 2005 Andi Kleen, SUSE Labs. | |
10 | * Copyright 2007 Jiri Kosina, SUSE Labs. | |
11 | * | |
12 | * This program is free software; you can redistribute it and/or modify | |
13 | * it under the terms of the GNU General Public License as published by | |
14 | * the Free Software Foundation; either version 2 of the License, or | |
15 | * (at your option) any later version. | |
16 | * | |
17 | * This program is distributed in the hope that it will be useful, | |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | * GNU General Public License for more details. | |
21 | * | |
22 | * You should have received a copy of the GNU General Public License | |
23 | * along with this program; if not, write to the Free Software | |
24 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
8817210d | 25 | */ |
cc503c1b JK |
26 | |
27 | #include <linux/personality.h> | |
8817210d | 28 | #include <linux/mm.h> |
8817210d | 29 | #include <linux/random.h> |
cc503c1b | 30 | #include <linux/limits.h> |
3f07c014 | 31 | #include <linux/sched/signal.h> |
01042607 | 32 | #include <linux/sched/mm.h> |
80938332 MH |
33 | #include <asm/elf.h> |
34 | ||
cc99535e | 35 | struct va_alignment __read_mostly va_align = { |
9387f774 BP |
36 | .flags = -1, |
37 | }; | |
38 | ||
4e7c22d4 | 39 | static unsigned long stack_maxrandom_size(void) |
80938332 | 40 | { |
4e7c22d4 | 41 | unsigned long max = 0; |
80938332 MH |
42 | if ((current->flags & PF_RANDOMIZE) && |
43 | !(current->personality & ADDR_NO_RANDOMIZE)) { | |
4e7c22d4 | 44 | max = ((-1UL) & STACK_RND_MASK) << PAGE_SHIFT; |
80938332 MH |
45 | } |
46 | ||
47 | return max; | |
48 | } | |
49 | ||
cc503c1b JK |
50 | /* |
51 | * Top of mmap area (just below the process stack). | |
52 | * | |
80938332 | 53 | * Leave an at least ~128 MB hole with possible stack randomization. |
cc503c1b | 54 | */ |
80938332 | 55 | #define MIN_GAP (128*1024*1024UL + stack_maxrandom_size()) |
cc503c1b | 56 | #define MAX_GAP (TASK_SIZE/6*5) |
8817210d | 57 | |
6a0b41d1 DS |
58 | #ifdef CONFIG_COMPAT |
59 | # define mmap32_rnd_bits mmap_rnd_compat_bits | |
60 | # define mmap64_rnd_bits mmap_rnd_bits | |
61 | #else | |
62 | # define mmap32_rnd_bits mmap_rnd_bits | |
63 | # define mmap64_rnd_bits mmap_rnd_bits | |
64 | #endif | |
65 | ||
954683a2 | 66 | static int mmap_is_legacy(void) |
cc503c1b JK |
67 | { |
68 | if (current->personality & ADDR_COMPAT_LAYOUT) | |
69 | return 1; | |
70 | ||
2854e72b | 71 | if (rlimit(RLIMIT_STACK) == RLIM_INFINITY) |
cc503c1b JK |
72 | return 1; |
73 | ||
74 | return sysctl_legacy_va_layout; | |
75 | } | |
76 | ||
6a0b41d1 | 77 | static unsigned long arch_rnd(unsigned int rndbits) |
675a0813 | 78 | { |
6a0b41d1 DS |
79 | return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT; |
80 | } | |
82168140 | 81 | |
6a0b41d1 DS |
82 | unsigned long arch_mmap_rnd(void) |
83 | { | |
84 | return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits); | |
675a0813 HH |
85 | } |
86 | ||
82168140 | 87 | static unsigned long mmap_base(unsigned long rnd) |
675a0813 | 88 | { |
2854e72b | 89 | unsigned long gap = rlimit(RLIMIT_STACK); |
675a0813 HH |
90 | |
91 | if (gap < MIN_GAP) | |
92 | gap = MIN_GAP; | |
93 | else if (gap > MAX_GAP) | |
94 | gap = MAX_GAP; | |
95 | ||
82168140 | 96 | return PAGE_ALIGN(TASK_SIZE - gap - rnd); |
675a0813 HH |
97 | } |
98 | ||
cc503c1b JK |
99 | /* |
100 | * This function, called very early during the creation of a new | |
101 | * process VM image, sets up which VM layout function to use: | |
102 | */ | |
103 | void arch_pick_mmap_layout(struct mm_struct *mm) | |
104 | { | |
82168140 KC |
105 | unsigned long random_factor = 0UL; |
106 | ||
107 | if (current->flags & PF_RANDOMIZE) | |
2b68f6ca | 108 | random_factor = arch_mmap_rnd(); |
82168140 | 109 | |
8b8addf8 | 110 | mm->mmap_legacy_base = TASK_UNMAPPED_BASE + random_factor; |
41aacc1e | 111 | |
675a0813 | 112 | if (mmap_is_legacy()) { |
41aacc1e | 113 | mm->mmap_base = mm->mmap_legacy_base; |
cc503c1b | 114 | mm->get_unmapped_area = arch_get_unmapped_area; |
cc503c1b | 115 | } else { |
82168140 | 116 | mm->mmap_base = mmap_base(random_factor); |
cc503c1b | 117 | mm->get_unmapped_area = arch_get_unmapped_area_topdown; |
cc503c1b | 118 | } |
8817210d | 119 | } |
a8965276 KS |
120 | |
121 | const char *arch_vma_name(struct vm_area_struct *vma) | |
122 | { | |
123 | if (vma->vm_flags & VM_MPX) | |
124 | return "[mpx]"; | |
125 | return NULL; | |
126 | } |