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 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 = ksys_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_32bit_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_32bit_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 if (flags & MAP_FIXED) 140 return addr; 141 142 find_start_end(addr, flags, &begin, &end); 143 144 if (len > end) 145 return -ENOMEM; 146 147 if (addr) { 148 addr = PAGE_ALIGN(addr); 149 vma = find_vma(mm, addr); 150 if (end - len >= addr && 151 (!vma || addr + len <= vm_start_gap(vma))) 152 return addr; 153 } 154 155 info.flags = 0; 156 info.length = len; 157 info.low_limit = begin; 158 info.high_limit = end; 159 info.align_mask = 0; 160 info.align_offset = pgoff << PAGE_SHIFT; 161 if (filp) { 162 info.align_mask = get_align_mask(); 163 info.align_offset += get_align_bits(); 164 } 165 return vm_unmapped_area(&info); 166 } 167 168 unsigned long 169 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 170 const unsigned long len, const unsigned long pgoff, 171 const unsigned long flags) 172 { 173 struct vm_area_struct *vma; 174 struct mm_struct *mm = current->mm; 175 unsigned long addr = addr0; 176 struct vm_unmapped_area_info info; 177 178 /* requested length too big for entire address space */ 179 if (len > TASK_SIZE) 180 return -ENOMEM; 181 182 /* No address checking. See comment at mmap_address_hint_valid() */ 183 if (flags & MAP_FIXED) 184 return addr; 185 186 /* for MAP_32BIT mappings we force the legacy mmap base */ 187 if (!in_32bit_syscall() && (flags & MAP_32BIT)) 188 goto bottomup; 189 190 /* requesting a specific address */ 191 if (addr) { 192 addr &= PAGE_MASK; 193 if (!mmap_address_hint_valid(addr, len)) 194 goto get_unmapped_area; 195 196 vma = find_vma(mm, addr); 197 if (!vma || addr + len <= vm_start_gap(vma)) 198 return addr; 199 } 200 get_unmapped_area: 201 202 info.flags = VM_UNMAPPED_AREA_TOPDOWN; 203 info.length = len; 204 info.low_limit = PAGE_SIZE; 205 info.high_limit = get_mmap_base(0); 206 207 /* 208 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area 209 * in the full address space. 210 * 211 * !in_32bit_syscall() check to avoid high addresses for x32 212 * (and make it no op on native i386). 213 */ 214 if (addr > DEFAULT_MAP_WINDOW && !in_32bit_syscall()) 215 info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW; 216 217 info.align_mask = 0; 218 info.align_offset = pgoff << PAGE_SHIFT; 219 if (filp) { 220 info.align_mask = get_align_mask(); 221 info.align_offset += get_align_bits(); 222 } 223 addr = vm_unmapped_area(&info); 224 if (!(addr & ~PAGE_MASK)) 225 return addr; 226 VM_BUG_ON(addr != -ENOMEM); 227 228 bottomup: 229 /* 230 * A failed mmap() very likely causes application failure, 231 * so fall back to the bottom-up function here. This scenario 232 * can happen with large stack limits and large mmap() 233 * allocations. 234 */ 235 return arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 236 } 237