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 | /* * Based on arch/arm/mm/mmap.c * * Copyright (C) 2012 ARM Ltd. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * 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, see <http://www.gnu.org/licenses/>. */ #include <linux/elf.h> #include <linux/fs.h> #include <linux/mm.h> #include <linux/mman.h> #include <linux/export.h> #include <linux/shm.h> #include <linux/sched.h> #include <linux/io.h> #include <linux/personality.h> #include <linux/random.h> #include <asm/cputype.h> /* * Leave enough space between the mmap area and the stack to honour ulimit in * the face of randomisation. */ #define MIN_GAP (SZ_128M + ((STACK_RND_MASK << PAGE_SHIFT) + 1)) #define MAX_GAP (STACK_TOP/6*5) 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; } unsigned long arch_mmap_rnd(void) { unsigned long rnd; #ifdef [31mCONFIG_COMPAT[0m if (test_thread_flag(TIF_32BIT)) rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1); else #endif rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); return rnd << PAGE_SHIFT; } static unsigned long mmap_base(unsigned long rnd) { unsigned long gap = rlimit(RLIMIT_STACK); if (gap < MIN_GAP) gap = MIN_GAP; else if (gap > MAX_GAP) gap = MAX_GAP; return PAGE_ALIGN(STACK_TOP - gap - rnd); } /* * 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(); /* * 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 + random_factor; 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; } } /* * You really shouldn't be using read() or write() on /dev/mem. This might go * away in the future. */ int valid_phys_addr_range(phys_addr_t addr, size_t size) { if (addr < PHYS_OFFSET) return 0; if (addr + size > __pa(high_memory - 1) + 1) return 0; return 1; } /* * Do not allow /dev/mem mappings beyond the supported physical range. */ int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) { return !(((pfn << PAGE_SHIFT) + size) & ~PHYS_MASK); } #ifdef [31mCONFIG_STRICT_DEVMEM[0m #include <linux/ioport.h> /* * devmem_is_allowed() checks to see if /dev/mem access to a certain address * is valid. The argument is a physical page number. We mimic x86 here by * disallowing access to system RAM as well as device-exclusive MMIO regions. * This effectively disable read()/write() on /dev/mem. */ int devmem_is_allowed(unsigned long pfn) { if (iomem_is_exclusive(pfn << PAGE_SHIFT)) return 0; if (!page_is_ram(pfn)) return 1; return 0; } #endif |