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 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 = sys_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 flags, unsigned long *begin, 104 unsigned long *end) 105 { 106 if (!in_compat_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 *end = in_compat_syscall() ? tasksize_32bit() : tasksize_64bit(); 124 } 125 126 unsigned long 127 arch_get_unmapped_area(struct file *filp, unsigned long addr, 128 unsigned long len, unsigned long pgoff, unsigned long flags) 129 { 130 struct mm_struct *mm = current->mm; 131 struct vm_area_struct *vma; 132 struct vm_unmapped_area_info info; 133 unsigned long begin, end; 134 135 if (flags & MAP_FIXED) 136 return addr; 137 138 find_start_end(flags, &begin, &end); 139 140 if (len > end) 141 return -ENOMEM; 142 143 if (addr) { 144 addr = PAGE_ALIGN(addr); 145 vma = find_vma(mm, addr); 146 if (end - len >= addr && 147 (!vma || addr + len <= vm_start_gap(vma))) 148 return addr; 149 } 150 151 info.flags = 0; 152 info.length = len; 153 info.low_limit = begin; 154 info.high_limit = end; 155 info.align_mask = 0; 156 info.align_offset = pgoff << PAGE_SHIFT; 157 if (filp) { 158 info.align_mask = get_align_mask(); 159 info.align_offset += get_align_bits(); 160 } 161 return vm_unmapped_area(&info); 162 } 163 164 unsigned long 165 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 166 const unsigned long len, const unsigned long pgoff, 167 const unsigned long flags) 168 { 169 struct vm_area_struct *vma; 170 struct mm_struct *mm = current->mm; 171 unsigned long addr = addr0; 172 struct vm_unmapped_area_info info; 173 174 /* requested length too big for entire address space */ 175 if (len > TASK_SIZE) 176 return -ENOMEM; 177 178 if (flags & MAP_FIXED) 179 return addr; 180 181 /* for MAP_32BIT mappings we force the legacy mmap base */ 182 if (!in_compat_syscall() && (flags & MAP_32BIT)) 183 goto bottomup; 184 185 /* requesting a specific address */ 186 if (addr) { 187 addr = PAGE_ALIGN(addr); 188 vma = find_vma(mm, addr); 189 if (TASK_SIZE - len >= addr && 190 (!vma || addr + len <= vm_start_gap(vma))) 191 return addr; 192 } 193 194 info.flags = VM_UNMAPPED_AREA_TOPDOWN; 195 info.length = len; 196 info.low_limit = PAGE_SIZE; 197 info.high_limit = get_mmap_base(0); 198 info.align_mask = 0; 199 info.align_offset = pgoff << PAGE_SHIFT; 200 if (filp) { 201 info.align_mask = get_align_mask(); 202 info.align_offset += get_align_bits(); 203 } 204 addr = vm_unmapped_area(&info); 205 if (!(addr & ~PAGE_MASK)) 206 return addr; 207 VM_BUG_ON(addr != -ENOMEM); 208 209 bottomup: 210 /* 211 * A failed mmap() very likely causes application failure, 212 * so fall back to the bottom-up function here. This scenario 213 * can happen with large stack limits and large mmap() 214 * allocations. 215 */ 216 return arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 217 } 218