1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/compat.h> 3 #include <linux/errno.h> 4 #include <linux/sched.h> 5 #include <linux/sched/mm.h> 6 #include <linux/syscalls.h> 7 #include <linux/mm.h> 8 #include <linux/fs.h> 9 #include <linux/smp.h> 10 #include <linux/sem.h> 11 #include <linux/msg.h> 12 #include <linux/shm.h> 13 #include <linux/stat.h> 14 #include <linux/mman.h> 15 #include <linux/file.h> 16 #include <linux/utsname.h> 17 #include <linux/personality.h> 18 #include <linux/random.h> 19 #include <linux/uaccess.h> 20 #include <linux/elf.h> 21 22 #include <asm/elf.h> 23 #include <asm/ia32.h> 24 25 /* 26 * Align a virtual address to avoid aliasing in the I$ on AMD F15h. 27 */ 28 static unsigned long get_align_mask(void) 29 { 30 /* handle 32- and 64-bit case with a single conditional */ 31 if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32()))) 32 return 0; 33 34 if (!(current->flags & PF_RANDOMIZE)) 35 return 0; 36 37 return va_align.mask; 38 } 39 40 /* 41 * To avoid aliasing in the I$ on AMD F15h, the bits defined by the 42 * va_align.bits, [12:upper_bit), are set to a random value instead of 43 * zeroing them. This random value is computed once per boot. This form 44 * of ASLR is known as "per-boot ASLR". 45 * 46 * To achieve this, the random value is added to the info.align_offset 47 * value before calling vm_unmapped_area() or ORed directly to the 48 * address. 49 */ 50 static unsigned long get_align_bits(void) 51 { 52 return va_align.bits & get_align_mask(); 53 } 54 55 unsigned long align_vdso_addr(unsigned long addr) 56 { 57 unsigned long align_mask = get_align_mask(); 58 addr = (addr + align_mask) & ~align_mask; 59 return addr | get_align_bits(); 60 } 61 62 static int __init control_va_addr_alignment(char *str) 63 { 64 /* guard against enabling this on other CPU families */ 65 if (va_align.flags < 0) 66 return 1; 67 68 if (*str == 0) 69 return 1; 70 71 if (*str == '=') 72 str++; 73 74 if (!strcmp(str, "32")) 75 va_align.flags = ALIGN_VA_32; 76 else if (!strcmp(str, "64")) 77 va_align.flags = ALIGN_VA_64; 78 else if (!strcmp(str, "off")) 79 va_align.flags = 0; 80 else if (!strcmp(str, "on")) 81 va_align.flags = ALIGN_VA_32 | ALIGN_VA_64; 82 else 83 return 0; 84 85 return 1; 86 } 87 __setup("align_va_addr", control_va_addr_alignment); 88 89 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len, 90 unsigned long, prot, unsigned long, flags, 91 unsigned long, fd, unsigned long, off) 92 { 93 if (off & ~PAGE_MASK) 94 return -EINVAL; 95 96 return ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT); 97 } 98 99 static void find_start_end(unsigned long addr, unsigned long flags, 100 unsigned long *begin, unsigned long *end) 101 { 102 if (!in_32bit_syscall() && (flags & MAP_32BIT)) { 103 /* This is usually used needed to map code in small 104 model, so it needs to be in the first 31bit. Limit 105 it to that. This means we need to move the 106 unmapped base down for this case. This can give 107 conflicts with the heap, but we assume that glibc 108 malloc knows how to fall back to mmap. Give it 1GB 109 of playground for now. -AK */ 110 *begin = 0x40000000; 111 *end = 0x80000000; 112 if (current->flags & PF_RANDOMIZE) { 113 *begin = randomize_page(*begin, 0x02000000); 114 } 115 return; 116 } 117 118 *begin = get_mmap_base(1); 119 if (in_32bit_syscall()) 120 *end = task_size_32bit(); 121 else 122 *end = task_size_64bit(addr > DEFAULT_MAP_WINDOW); 123 } 124 125 unsigned long 126 arch_get_unmapped_area(struct file *filp, unsigned long addr, 127 unsigned long len, unsigned long pgoff, unsigned long flags) 128 { 129 struct mm_struct *mm = current->mm; 130 struct vm_area_struct *vma; 131 struct vm_unmapped_area_info info; 132 unsigned long begin, end; 133 134 if (flags & MAP_FIXED) 135 return addr; 136 137 find_start_end(addr, flags, &begin, &end); 138 139 if (len > end) 140 return -ENOMEM; 141 142 if (addr) { 143 addr = PAGE_ALIGN(addr); 144 vma = find_vma(mm, addr); 145 if (end - len >= addr && 146 (!vma || addr + len <= vm_start_gap(vma))) 147 return addr; 148 } 149 150 info.flags = 0; 151 info.length = len; 152 info.low_limit = begin; 153 info.high_limit = end; 154 info.align_mask = 0; 155 info.align_offset = pgoff << PAGE_SHIFT; 156 if (filp) { 157 info.align_mask = get_align_mask(); 158 info.align_offset += get_align_bits(); 159 } 160 return vm_unmapped_area(&info); 161 } 162 163 unsigned long 164 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 165 const unsigned long len, const unsigned long pgoff, 166 const unsigned long flags) 167 { 168 struct vm_area_struct *vma; 169 struct mm_struct *mm = current->mm; 170 unsigned long addr = addr0; 171 struct vm_unmapped_area_info info; 172 173 /* requested length too big for entire address space */ 174 if (len > TASK_SIZE) 175 return -ENOMEM; 176 177 /* No address checking. See comment at mmap_address_hint_valid() */ 178 if (flags & MAP_FIXED) 179 return addr; 180 181 /* for MAP_32BIT mappings we force the legacy mmap base */ 182 if (!in_32bit_syscall() && (flags & MAP_32BIT)) 183 goto bottomup; 184 185 /* requesting a specific address */ 186 if (addr) { 187 addr &= PAGE_MASK; 188 if (!mmap_address_hint_valid(addr, len)) 189 goto get_unmapped_area; 190 191 vma = find_vma(mm, addr); 192 if (!vma || addr + len <= vm_start_gap(vma)) 193 return addr; 194 } 195 get_unmapped_area: 196 197 info.flags = VM_UNMAPPED_AREA_TOPDOWN; 198 info.length = len; 199 info.low_limit = PAGE_SIZE; 200 info.high_limit = get_mmap_base(0); 201 202 /* 203 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area 204 * in the full address space. 205 * 206 * !in_32bit_syscall() check to avoid high addresses for x32 207 * (and make it no op on native i386). 208 */ 209 if (addr > DEFAULT_MAP_WINDOW && !in_32bit_syscall()) 210 info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW; 211 212 info.align_mask = 0; 213 info.align_offset = pgoff << PAGE_SHIFT; 214 if (filp) { 215 info.align_mask = get_align_mask(); 216 info.align_offset += get_align_bits(); 217 } 218 addr = vm_unmapped_area(&info); 219 if (!(addr & ~PAGE_MASK)) 220 return addr; 221 VM_BUG_ON(addr != -ENOMEM); 222 223 bottomup: 224 /* 225 * A failed mmap() very likely causes application failure, 226 * so fall back to the bottom-up function here. This scenario 227 * can happen with large stack limits and large mmap() 228 * allocations. 229 */ 230 return arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 231 } 232