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 #include <asm/syscalls.h> 25 #include <asm/mpx.h> 26 27 /* 28 * Align a virtual address to avoid aliasing in the I$ on AMD F15h. 29 */ 30 static unsigned long get_align_mask(void) 31 { 32 /* handle 32- and 64-bit case with a single conditional */ 33 if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32()))) 34 return 0; 35 36 if (!(current->flags & PF_RANDOMIZE)) 37 return 0; 38 39 return va_align.mask; 40 } 41 42 /* 43 * To avoid aliasing in the I$ on AMD F15h, the bits defined by the 44 * va_align.bits, [12:upper_bit), are set to a random value instead of 45 * zeroing them. This random value is computed once per boot. This form 46 * of ASLR is known as "per-boot ASLR". 47 * 48 * To achieve this, the random value is added to the info.align_offset 49 * value before calling vm_unmapped_area() or ORed directly to the 50 * address. 51 */ 52 static unsigned long get_align_bits(void) 53 { 54 return va_align.bits & get_align_mask(); 55 } 56 57 unsigned long align_vdso_addr(unsigned long addr) 58 { 59 unsigned long align_mask = get_align_mask(); 60 addr = (addr + align_mask) & ~align_mask; 61 return addr | get_align_bits(); 62 } 63 64 static int __init control_va_addr_alignment(char *str) 65 { 66 /* guard against enabling this on other CPU families */ 67 if (va_align.flags < 0) 68 return 1; 69 70 if (*str == 0) 71 return 1; 72 73 if (*str == '=') 74 str++; 75 76 if (!strcmp(str, "32")) 77 va_align.flags = ALIGN_VA_32; 78 else if (!strcmp(str, "64")) 79 va_align.flags = ALIGN_VA_64; 80 else if (!strcmp(str, "off")) 81 va_align.flags = 0; 82 else if (!strcmp(str, "on")) 83 va_align.flags = ALIGN_VA_32 | ALIGN_VA_64; 84 else 85 return 0; 86 87 return 1; 88 } 89 __setup("align_va_addr", control_va_addr_alignment); 90 91 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len, 92 unsigned long, prot, unsigned long, flags, 93 unsigned long, fd, unsigned long, off) 94 { 95 long error; 96 error = -EINVAL; 97 if (off & ~PAGE_MASK) 98 goto out; 99 100 error = ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT); 101 out: 102 return error; 103 } 104 105 static void find_start_end(unsigned long addr, unsigned long flags, 106 unsigned long *begin, unsigned long *end) 107 { 108 if (!in_compat_syscall() && (flags & MAP_32BIT)) { 109 /* This is usually used needed to map code in small 110 model, so it needs to be in the first 31bit. Limit 111 it to that. This means we need to move the 112 unmapped base down for this case. This can give 113 conflicts with the heap, but we assume that glibc 114 malloc knows how to fall back to mmap. Give it 1GB 115 of playground for now. -AK */ 116 *begin = 0x40000000; 117 *end = 0x80000000; 118 if (current->flags & PF_RANDOMIZE) { 119 *begin = randomize_page(*begin, 0x02000000); 120 } 121 return; 122 } 123 124 *begin = get_mmap_base(1); 125 if (in_compat_syscall()) 126 *end = task_size_32bit(); 127 else 128 *end = task_size_64bit(addr > DEFAULT_MAP_WINDOW); 129 } 130 131 unsigned long 132 arch_get_unmapped_area(struct file *filp, unsigned long addr, 133 unsigned long len, unsigned long pgoff, unsigned long flags) 134 { 135 struct mm_struct *mm = current->mm; 136 struct vm_area_struct *vma; 137 struct vm_unmapped_area_info info; 138 unsigned long begin, end; 139 140 addr = mpx_unmapped_area_check(addr, len, flags); 141 if (IS_ERR_VALUE(addr)) 142 return addr; 143 144 if (flags & MAP_FIXED) 145 return addr; 146 147 find_start_end(addr, flags, &begin, &end); 148 149 if (len > end) 150 return -ENOMEM; 151 152 if (addr) { 153 addr = PAGE_ALIGN(addr); 154 vma = find_vma(mm, addr); 155 if (end - len >= addr && 156 (!vma || addr + len <= vm_start_gap(vma))) 157 return addr; 158 } 159 160 info.flags = 0; 161 info.length = len; 162 info.low_limit = begin; 163 info.high_limit = end; 164 info.align_mask = 0; 165 info.align_offset = pgoff << PAGE_SHIFT; 166 if (filp) { 167 info.align_mask = get_align_mask(); 168 info.align_offset += get_align_bits(); 169 } 170 return vm_unmapped_area(&info); 171 } 172 173 unsigned long 174 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 175 const unsigned long len, const unsigned long pgoff, 176 const unsigned long flags) 177 { 178 struct vm_area_struct *vma; 179 struct mm_struct *mm = current->mm; 180 unsigned long addr = addr0; 181 struct vm_unmapped_area_info info; 182 183 addr = mpx_unmapped_area_check(addr, len, flags); 184 if (IS_ERR_VALUE(addr)) 185 return addr; 186 187 /* requested length too big for entire address space */ 188 if (len > TASK_SIZE) 189 return -ENOMEM; 190 191 /* No address checking. See comment at mmap_address_hint_valid() */ 192 if (flags & MAP_FIXED) 193 return addr; 194 195 /* for MAP_32BIT mappings we force the legacy mmap base */ 196 if (!in_compat_syscall() && (flags & MAP_32BIT)) 197 goto bottomup; 198 199 /* requesting a specific address */ 200 if (addr) { 201 addr &= PAGE_MASK; 202 if (!mmap_address_hint_valid(addr, len)) 203 goto get_unmapped_area; 204 205 vma = find_vma(mm, addr); 206 if (!vma || addr + len <= vm_start_gap(vma)) 207 return addr; 208 } 209 get_unmapped_area: 210 211 info.flags = VM_UNMAPPED_AREA_TOPDOWN; 212 info.length = len; 213 info.low_limit = PAGE_SIZE; 214 info.high_limit = get_mmap_base(0); 215 216 /* 217 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area 218 * in the full address space. 219 * 220 * !in_compat_syscall() check to avoid high addresses for x32. 221 */ 222 if (addr > DEFAULT_MAP_WINDOW && !in_compat_syscall()) 223 info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW; 224 225 info.align_mask = 0; 226 info.align_offset = pgoff << PAGE_SHIFT; 227 if (filp) { 228 info.align_mask = get_align_mask(); 229 info.align_offset += get_align_bits(); 230 } 231 addr = vm_unmapped_area(&info); 232 if (!(addr & ~PAGE_MASK)) 233 return addr; 234 VM_BUG_ON(addr != -ENOMEM); 235 236 bottomup: 237 /* 238 * A failed mmap() very likely causes application failure, 239 * so fall back to the bottom-up function here. This scenario 240 * can happen with large stack limits and large mmap() 241 * allocations. 242 */ 243 return arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 244 } 245