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 long error; 94 error = -EINVAL; 95 if (off & ~PAGE_MASK) 96 goto out; 97 98 error = ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT); 99 out: 100 return error; 101 } 102 103 static void find_start_end(unsigned long addr, unsigned long flags, 104 unsigned long *begin, unsigned long *end) 105 { 106 if (!in_32bit_syscall() && (flags & MAP_32BIT)) { 107 /* This is usually used needed to map code in small 108 model, so it needs to be in the first 31bit. Limit 109 it to that. This means we need to move the 110 unmapped base down for this case. This can give 111 conflicts with the heap, but we assume that glibc 112 malloc knows how to fall back to mmap. Give it 1GB 113 of playground for now. -AK */ 114 *begin = 0x40000000; 115 *end = 0x80000000; 116 if (current->flags & PF_RANDOMIZE) { 117 *begin = randomize_page(*begin, 0x02000000); 118 } 119 return; 120 } 121 122 *begin = get_mmap_base(1); 123 if (in_32bit_syscall()) 124 *end = task_size_32bit(); 125 else 126 *end = task_size_64bit(addr > DEFAULT_MAP_WINDOW); 127 } 128 129 unsigned long 130 arch_get_unmapped_area(struct file *filp, unsigned long addr, 131 unsigned long len, unsigned long pgoff, unsigned long flags) 132 { 133 struct mm_struct *mm = current->mm; 134 struct vm_area_struct *vma; 135 struct vm_unmapped_area_info info; 136 unsigned long begin, end; 137 138 if (flags & MAP_FIXED) 139 return addr; 140 141 find_start_end(addr, flags, &begin, &end); 142 143 if (len > end) 144 return -ENOMEM; 145 146 if (addr) { 147 addr = PAGE_ALIGN(addr); 148 vma = find_vma(mm, addr); 149 if (end - len >= addr && 150 (!vma || addr + len <= vm_start_gap(vma))) 151 return addr; 152 } 153 154 info.flags = 0; 155 info.length = len; 156 info.low_limit = begin; 157 info.high_limit = end; 158 info.align_mask = 0; 159 info.align_offset = pgoff << PAGE_SHIFT; 160 if (filp) { 161 info.align_mask = get_align_mask(); 162 info.align_offset += get_align_bits(); 163 } 164 return vm_unmapped_area(&info); 165 } 166 167 unsigned long 168 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 169 const unsigned long len, const unsigned long pgoff, 170 const unsigned long flags) 171 { 172 struct vm_area_struct *vma; 173 struct mm_struct *mm = current->mm; 174 unsigned long addr = addr0; 175 struct vm_unmapped_area_info info; 176 177 /* requested length too big for entire address space */ 178 if (len > TASK_SIZE) 179 return -ENOMEM; 180 181 /* No address checking. See comment at mmap_address_hint_valid() */ 182 if (flags & MAP_FIXED) 183 return addr; 184 185 /* for MAP_32BIT mappings we force the legacy mmap base */ 186 if (!in_32bit_syscall() && (flags & MAP_32BIT)) 187 goto bottomup; 188 189 /* requesting a specific address */ 190 if (addr) { 191 addr &= PAGE_MASK; 192 if (!mmap_address_hint_valid(addr, len)) 193 goto get_unmapped_area; 194 195 vma = find_vma(mm, addr); 196 if (!vma || addr + len <= vm_start_gap(vma)) 197 return addr; 198 } 199 get_unmapped_area: 200 201 info.flags = VM_UNMAPPED_AREA_TOPDOWN; 202 info.length = len; 203 info.low_limit = PAGE_SIZE; 204 info.high_limit = get_mmap_base(0); 205 206 /* 207 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area 208 * in the full address space. 209 * 210 * !in_32bit_syscall() check to avoid high addresses for x32 211 * (and make it no op on native i386). 212 */ 213 if (addr > DEFAULT_MAP_WINDOW && !in_32bit_syscall()) 214 info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW; 215 216 info.align_mask = 0; 217 info.align_offset = pgoff << PAGE_SHIFT; 218 if (filp) { 219 info.align_mask = get_align_mask(); 220 info.align_offset += get_align_bits(); 221 } 222 addr = vm_unmapped_area(&info); 223 if (!(addr & ~PAGE_MASK)) 224 return addr; 225 VM_BUG_ON(addr != -ENOMEM); 226 227 bottomup: 228 /* 229 * A failed mmap() very likely causes application failure, 230 * so fall back to the bottom-up function here. This scenario 231 * can happen with large stack limits and large mmap() 232 * allocations. 233 */ 234 return arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 235 } 236