1 #include <linux/errno.h> 2 #include <linux/sched.h> 3 #include <linux/sched/mm.h> 4 #include <linux/syscalls.h> 5 #include <linux/mm.h> 6 #include <linux/fs.h> 7 #include <linux/smp.h> 8 #include <linux/sem.h> 9 #include <linux/msg.h> 10 #include <linux/shm.h> 11 #include <linux/stat.h> 12 #include <linux/mman.h> 13 #include <linux/file.h> 14 #include <linux/utsname.h> 15 #include <linux/personality.h> 16 #include <linux/random.h> 17 #include <linux/uaccess.h> 18 #include <linux/elf.h> 19 20 #include <asm/elf.h> 21 #include <asm/compat.h> 22 #include <asm/ia32.h> 23 #include <asm/syscalls.h> 24 #include <asm/mpx.h> 25 26 /* 27 * Align a virtual address to avoid aliasing in the I$ on AMD F15h. 28 */ 29 static unsigned long get_align_mask(void) 30 { 31 /* handle 32- and 64-bit case with a single conditional */ 32 if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32()))) 33 return 0; 34 35 if (!(current->flags & PF_RANDOMIZE)) 36 return 0; 37 38 return va_align.mask; 39 } 40 41 /* 42 * To avoid aliasing in the I$ on AMD F15h, the bits defined by the 43 * va_align.bits, [12:upper_bit), are set to a random value instead of 44 * zeroing them. This random value is computed once per boot. This form 45 * of ASLR is known as "per-boot ASLR". 46 * 47 * To achieve this, the random value is added to the info.align_offset 48 * value before calling vm_unmapped_area() or ORed directly to the 49 * address. 50 */ 51 static unsigned long get_align_bits(void) 52 { 53 return va_align.bits & get_align_mask(); 54 } 55 56 unsigned long align_vdso_addr(unsigned long addr) 57 { 58 unsigned long align_mask = get_align_mask(); 59 addr = (addr + align_mask) & ~align_mask; 60 return addr | get_align_bits(); 61 } 62 63 static int __init control_va_addr_alignment(char *str) 64 { 65 /* guard against enabling this on other CPU families */ 66 if (va_align.flags < 0) 67 return 1; 68 69 if (*str == 0) 70 return 1; 71 72 if (*str == '=') 73 str++; 74 75 if (!strcmp(str, "32")) 76 va_align.flags = ALIGN_VA_32; 77 else if (!strcmp(str, "64")) 78 va_align.flags = ALIGN_VA_64; 79 else if (!strcmp(str, "off")) 80 va_align.flags = 0; 81 else if (!strcmp(str, "on")) 82 va_align.flags = ALIGN_VA_32 | ALIGN_VA_64; 83 else 84 return 0; 85 86 return 1; 87 } 88 __setup("align_va_addr", control_va_addr_alignment); 89 90 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len, 91 unsigned long, prot, unsigned long, flags, 92 unsigned long, fd, unsigned long, off) 93 { 94 long error; 95 error = -EINVAL; 96 if (off & ~PAGE_MASK) 97 goto out; 98 99 error = sys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT); 100 out: 101 return error; 102 } 103 104 static void find_start_end(unsigned long addr, unsigned long flags, 105 unsigned long *begin, unsigned long *end) 106 { 107 if (!in_compat_syscall() && (flags & MAP_32BIT)) { 108 /* This is usually used needed to map code in small 109 model, so it needs to be in the first 31bit. Limit 110 it to that. This means we need to move the 111 unmapped base down for this case. This can give 112 conflicts with the heap, but we assume that glibc 113 malloc knows how to fall back to mmap. Give it 1GB 114 of playground for now. -AK */ 115 *begin = 0x40000000; 116 *end = 0x80000000; 117 if (current->flags & PF_RANDOMIZE) { 118 *begin = randomize_page(*begin, 0x02000000); 119 } 120 return; 121 } 122 123 *begin = get_mmap_base(1); 124 if (in_compat_syscall()) 125 *end = task_size_32bit(); 126 else 127 *end = task_size_64bit(addr > DEFAULT_MAP_WINDOW); 128 } 129 130 unsigned long 131 arch_get_unmapped_area(struct file *filp, unsigned long addr, 132 unsigned long len, unsigned long pgoff, unsigned long flags) 133 { 134 struct mm_struct *mm = current->mm; 135 struct vm_area_struct *vma; 136 struct vm_unmapped_area_info info; 137 unsigned long begin, end; 138 139 addr = mpx_unmapped_area_check(addr, len, flags); 140 if (IS_ERR_VALUE(addr)) 141 return addr; 142 143 if (flags & MAP_FIXED) 144 return addr; 145 146 find_start_end(addr, flags, &begin, &end); 147 148 if (len > end) 149 return -ENOMEM; 150 151 if (addr) { 152 addr = PAGE_ALIGN(addr); 153 vma = find_vma(mm, addr); 154 if (end - len >= addr && 155 (!vma || addr + len <= vm_start_gap(vma))) 156 return addr; 157 } 158 159 info.flags = 0; 160 info.length = len; 161 info.low_limit = begin; 162 info.high_limit = end; 163 info.align_mask = 0; 164 info.align_offset = pgoff << PAGE_SHIFT; 165 if (filp) { 166 info.align_mask = get_align_mask(); 167 info.align_offset += get_align_bits(); 168 } 169 return vm_unmapped_area(&info); 170 } 171 172 unsigned long 173 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 174 const unsigned long len, const unsigned long pgoff, 175 const unsigned long flags) 176 { 177 struct vm_area_struct *vma; 178 struct mm_struct *mm = current->mm; 179 unsigned long addr = addr0; 180 struct vm_unmapped_area_info info; 181 182 addr = mpx_unmapped_area_check(addr, len, flags); 183 if (IS_ERR_VALUE(addr)) 184 return addr; 185 186 /* requested length too big for entire address space */ 187 if (len > TASK_SIZE) 188 return -ENOMEM; 189 190 if (flags & MAP_FIXED) 191 return addr; 192 193 /* for MAP_32BIT mappings we force the legacy mmap base */ 194 if (!in_compat_syscall() && (flags & MAP_32BIT)) 195 goto bottomup; 196 197 /* requesting a specific address */ 198 if (addr) { 199 addr = PAGE_ALIGN(addr); 200 vma = find_vma(mm, addr); 201 if (TASK_SIZE - len >= addr && 202 (!vma || addr + len <= vm_start_gap(vma))) 203 return addr; 204 } 205 206 info.flags = VM_UNMAPPED_AREA_TOPDOWN; 207 info.length = len; 208 info.low_limit = PAGE_SIZE; 209 info.high_limit = get_mmap_base(0); 210 211 /* 212 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area 213 * in the full address space. 214 * 215 * !in_compat_syscall() check to avoid high addresses for x32. 216 */ 217 if (addr > DEFAULT_MAP_WINDOW && !in_compat_syscall()) 218 info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW; 219 220 info.align_mask = 0; 221 info.align_offset = pgoff << PAGE_SHIFT; 222 if (filp) { 223 info.align_mask = get_align_mask(); 224 info.align_offset += get_align_bits(); 225 } 226 addr = vm_unmapped_area(&info); 227 if (!(addr & ~PAGE_MASK)) 228 return addr; 229 VM_BUG_ON(addr != -ENOMEM); 230 231 bottomup: 232 /* 233 * A failed mmap() very likely causes application failure, 234 * so fall back to the bottom-up function here. This scenario 235 * can happen with large stack limits and large mmap() 236 * allocations. 237 */ 238 return arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 239 } 240