Jiri Kosina | cc503c1 | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 1 | /* |
Harvey Harrison | 675a081 | 2008-01-30 13:31:10 +0100 | [diff] [blame] | 2 | * Flexible mmap layout support |
Jiri Kosina | cc503c1 | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 3 | * |
| 4 | * Based on code by Ingo Molnar and Andi Kleen, copyrighted |
| 5 | * as follows: |
| 6 | * |
Ingo Molnar | 8f47e16 | 2009-01-31 02:03:42 +0100 | [diff] [blame] | 7 | * Copyright 2003-2009 Red Hat Inc. |
Jiri Kosina | cc503c1 | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 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 |
Andi Kleen | 8817210 | 2006-01-17 07:03:38 +0100 | [diff] [blame] | 25 | */ |
Jiri Kosina | cc503c1 | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 26 | |
| 27 | #include <linux/personality.h> |
Andi Kleen | 8817210 | 2006-01-17 07:03:38 +0100 | [diff] [blame] | 28 | #include <linux/mm.h> |
Andi Kleen | 8817210 | 2006-01-17 07:03:38 +0100 | [diff] [blame] | 29 | #include <linux/random.h> |
Jiri Kosina | cc503c1 | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 30 | #include <linux/limits.h> |
| 31 | #include <linux/sched.h> |
Michal Hocko | 8093833 | 2009-09-08 11:01:55 +0200 | [diff] [blame] | 32 | #include <asm/elf.h> |
| 33 | |
Jan-Simon Möller | cc99535 | 2014-09-05 16:16:45 -0700 | [diff] [blame] | 34 | struct va_alignment __read_mostly va_align = { |
Borislav Petkov | 9387f77 | 2011-08-06 14:31:38 +0200 | [diff] [blame] | 35 | .flags = -1, |
| 36 | }; |
| 37 | |
Hector Marco-Gisbert | 4e7c22d | 2015-02-14 09:33:50 -0800 | [diff] [blame] | 38 | static unsigned long stack_maxrandom_size(void) |
Michal Hocko | 8093833 | 2009-09-08 11:01:55 +0200 | [diff] [blame] | 39 | { |
Hector Marco-Gisbert | 4e7c22d | 2015-02-14 09:33:50 -0800 | [diff] [blame] | 40 | unsigned long max = 0; |
Michal Hocko | 8093833 | 2009-09-08 11:01:55 +0200 | [diff] [blame] | 41 | if ((current->flags & PF_RANDOMIZE) && |
| 42 | !(current->personality & ADDR_NO_RANDOMIZE)) { |
Hector Marco-Gisbert | 4e7c22d | 2015-02-14 09:33:50 -0800 | [diff] [blame] | 43 | max = ((-1UL) & STACK_RND_MASK) << PAGE_SHIFT; |
Michal Hocko | 8093833 | 2009-09-08 11:01:55 +0200 | [diff] [blame] | 44 | } |
| 45 | |
| 46 | return max; |
| 47 | } |
| 48 | |
Jiri Kosina | cc503c1 | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 49 | /* |
| 50 | * Top of mmap area (just below the process stack). |
| 51 | * |
Michal Hocko | 8093833 | 2009-09-08 11:01:55 +0200 | [diff] [blame] | 52 | * Leave an at least ~128 MB hole with possible stack randomization. |
Jiri Kosina | cc503c1 | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 53 | */ |
Michal Hocko | 8093833 | 2009-09-08 11:01:55 +0200 | [diff] [blame] | 54 | #define MIN_GAP (128*1024*1024UL + stack_maxrandom_size()) |
Jiri Kosina | cc503c1 | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 55 | #define MAX_GAP (TASK_SIZE/6*5) |
Andi Kleen | 8817210 | 2006-01-17 07:03:38 +0100 | [diff] [blame] | 56 | |
Andrew Morton | 954683a | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 57 | static int mmap_is_legacy(void) |
Jiri Kosina | cc503c1 | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 58 | { |
| 59 | if (current->personality & ADDR_COMPAT_LAYOUT) |
| 60 | return 1; |
| 61 | |
Jiri Slaby | 2854e72 | 2010-01-27 17:32:22 +0100 | [diff] [blame] | 62 | if (rlimit(RLIMIT_STACK) == RLIM_INFINITY) |
Jiri Kosina | cc503c1 | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 63 | return 1; |
| 64 | |
| 65 | return sysctl_legacy_va_layout; |
| 66 | } |
| 67 | |
Kees Cook | 2b68f6c | 2015-04-14 15:48:00 -0700 | [diff] [blame] | 68 | unsigned long arch_mmap_rnd(void) |
Harvey Harrison | 675a081 | 2008-01-30 13:31:10 +0100 | [diff] [blame] | 69 | { |
Kees Cook | 8216814 | 2015-04-14 15:47:45 -0700 | [diff] [blame] | 70 | unsigned long rnd; |
Harvey Harrison | 675a081 | 2008-01-30 13:31:10 +0100 | [diff] [blame] | 71 | |
Kees Cook | 8216814 | 2015-04-14 15:47:45 -0700 | [diff] [blame] | 72 | if (mmap_is_ia32()) |
Daniel Cashman | 9e08f57 | 2016-01-14 15:20:06 -0800 | [diff] [blame] | 73 | #ifdef CONFIG_COMPAT |
Daniel Cashman | 5ef11c3 | 2016-02-26 15:19:37 -0800 | [diff] [blame] | 74 | rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1); |
Daniel Cashman | 9e08f57 | 2016-01-14 15:20:06 -0800 | [diff] [blame] | 75 | #else |
Daniel Cashman | 5ef11c3 | 2016-02-26 15:19:37 -0800 | [diff] [blame] | 76 | rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); |
Daniel Cashman | 9e08f57 | 2016-01-14 15:20:06 -0800 | [diff] [blame] | 77 | #endif |
Kees Cook | 8216814 | 2015-04-14 15:47:45 -0700 | [diff] [blame] | 78 | else |
Daniel Cashman | 5ef11c3 | 2016-02-26 15:19:37 -0800 | [diff] [blame] | 79 | rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); |
Kees Cook | 8216814 | 2015-04-14 15:47:45 -0700 | [diff] [blame] | 80 | |
Harvey Harrison | 675a081 | 2008-01-30 13:31:10 +0100 | [diff] [blame] | 81 | return rnd << PAGE_SHIFT; |
| 82 | } |
| 83 | |
Kees Cook | 8216814 | 2015-04-14 15:47:45 -0700 | [diff] [blame] | 84 | static unsigned long mmap_base(unsigned long rnd) |
Harvey Harrison | 675a081 | 2008-01-30 13:31:10 +0100 | [diff] [blame] | 85 | { |
Jiri Slaby | 2854e72 | 2010-01-27 17:32:22 +0100 | [diff] [blame] | 86 | unsigned long gap = rlimit(RLIMIT_STACK); |
Harvey Harrison | 675a081 | 2008-01-30 13:31:10 +0100 | [diff] [blame] | 87 | |
| 88 | if (gap < MIN_GAP) |
| 89 | gap = MIN_GAP; |
| 90 | else if (gap > MAX_GAP) |
| 91 | gap = MAX_GAP; |
| 92 | |
Kees Cook | 8216814 | 2015-04-14 15:47:45 -0700 | [diff] [blame] | 93 | return PAGE_ALIGN(TASK_SIZE - gap - rnd); |
Harvey Harrison | 675a081 | 2008-01-30 13:31:10 +0100 | [diff] [blame] | 94 | } |
| 95 | |
| 96 | /* |
Jiri Kosina | cc503c1 | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 97 | * This function, called very early during the creation of a new |
| 98 | * process VM image, sets up which VM layout function to use: |
| 99 | */ |
| 100 | void arch_pick_mmap_layout(struct mm_struct *mm) |
| 101 | { |
Kees Cook | 8216814 | 2015-04-14 15:47:45 -0700 | [diff] [blame] | 102 | unsigned long random_factor = 0UL; |
| 103 | |
| 104 | if (current->flags & PF_RANDOMIZE) |
Kees Cook | 2b68f6c | 2015-04-14 15:48:00 -0700 | [diff] [blame] | 105 | random_factor = arch_mmap_rnd(); |
Kees Cook | 8216814 | 2015-04-14 15:47:45 -0700 | [diff] [blame] | 106 | |
Hector Marco-Gisbert | 8b8addf | 2016-03-10 20:51:00 +0100 | [diff] [blame] | 107 | mm->mmap_legacy_base = TASK_UNMAPPED_BASE + random_factor; |
Radu Caragea | 41aacc1 | 2013-08-21 20:55:59 +0300 | [diff] [blame] | 108 | |
Harvey Harrison | 675a081 | 2008-01-30 13:31:10 +0100 | [diff] [blame] | 109 | if (mmap_is_legacy()) { |
Radu Caragea | 41aacc1 | 2013-08-21 20:55:59 +0300 | [diff] [blame] | 110 | mm->mmap_base = mm->mmap_legacy_base; |
Jiri Kosina | cc503c1 | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 111 | mm->get_unmapped_area = arch_get_unmapped_area; |
Jiri Kosina | cc503c1 | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 112 | } else { |
Kees Cook | 8216814 | 2015-04-14 15:47:45 -0700 | [diff] [blame] | 113 | mm->mmap_base = mmap_base(random_factor); |
Jiri Kosina | cc503c1 | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 114 | mm->get_unmapped_area = arch_get_unmapped_area_topdown; |
Jiri Kosina | cc503c1 | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 115 | } |
Jiri Kosina | cc503c1 | 2008-01-30 13:31:07 +0100 | [diff] [blame] | 116 | } |
Kirill A. Shutemov | a8965276 | 2015-07-20 14:29:58 -0700 | [diff] [blame] | 117 | |
| 118 | const char *arch_vma_name(struct vm_area_struct *vma) |
| 119 | { |
| 120 | if (vma->vm_flags & VM_MPX) |
| 121 | return "[mpx]"; |
| 122 | return NULL; |
| 123 | } |