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/ia32.h> 21 #include <asm/syscalls.h> 22 23 /* 24 * Align a virtual address to avoid aliasing in the I$ on AMD F15h. 25 */ 26 static unsigned long get_align_mask(void) 27 { 28 /* handle 32- and 64-bit case with a single conditional */ 29 if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32()))) 30 return 0; 31 32 if (!(current->flags & PF_RANDOMIZE)) 33 return 0; 34 35 return va_align.mask; 36 } 37 38 /* 39 * To avoid aliasing in the I$ on AMD F15h, the bits defined by the 40 * va_align.bits, [12:upper_bit), are set to a random value instead of 41 * zeroing them. This random value is computed once per boot. This form 42 * of ASLR is known as "per-boot ASLR". 43 * 44 * To achieve this, the random value is added to the info.align_offset 45 * value before calling vm_unmapped_area() or ORed directly to the 46 * address. 47 */ 48 static unsigned long get_align_bits(void) 49 { 50 return va_align.bits & get_align_mask(); 51 } 52 53 unsigned long align_vdso_addr(unsigned long addr) 54 { 55 unsigned long align_mask = get_align_mask(); 56 addr = (addr + align_mask) & ~align_mask; 57 return addr | get_align_bits(); 58 } 59 60 static int __init control_va_addr_alignment(char *str) 61 { 62 /* guard against enabling this on other CPU families */ 63 if (va_align.flags < 0) 64 return 1; 65 66 if (*str == 0) 67 return 1; 68 69 if (*str == '=') 70 str++; 71 72 if (!strcmp(str, "32")) 73 va_align.flags = ALIGN_VA_32; 74 else if (!strcmp(str, "64")) 75 va_align.flags = ALIGN_VA_64; 76 else if (!strcmp(str, "off")) 77 va_align.flags = 0; 78 else if (!strcmp(str, "on")) 79 va_align.flags = ALIGN_VA_32 | ALIGN_VA_64; 80 else 81 return 0; 82 83 return 1; 84 } 85 __setup("align_va_addr", control_va_addr_alignment); 86 87 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len, 88 unsigned long, prot, unsigned long, flags, 89 unsigned long, fd, unsigned long, off) 90 { 91 long error; 92 error = -EINVAL; 93 if (off & ~PAGE_MASK) 94 goto out; 95 96 error = sys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT); 97 out: 98 return error; 99 } 100 101 static void find_start_end(unsigned long flags, unsigned long *begin, 102 unsigned long *end) 103 { 104 if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT)) { 105 /* This is usually used needed to map code in small 106 model, so it needs to be in the first 31bit. Limit 107 it to that. This means we need to move the 108 unmapped base down for this case. This can give 109 conflicts with the heap, but we assume that glibc 110 malloc knows how to fall back to mmap. Give it 1GB 111 of playground for now. -AK */ 112 *begin = 0x40000000; 113 *end = 0x80000000; 114 if (current->flags & PF_RANDOMIZE) { 115 *begin = randomize_page(*begin, 0x02000000); 116 } 117 } else { 118 *begin = current->mm->mmap_legacy_base; 119 *end = TASK_SIZE; 120 } 121 } 122 123 unsigned long 124 arch_get_unmapped_area(struct file *filp, unsigned long addr, 125 unsigned long len, unsigned long pgoff, unsigned long flags) 126 { 127 struct mm_struct *mm = current->mm; 128 struct vm_area_struct *vma; 129 struct vm_unmapped_area_info info; 130 unsigned long begin, end; 131 132 if (flags & MAP_FIXED) 133 return addr; 134 135 find_start_end(flags, &begin, &end); 136 137 if (len > end) 138 return -ENOMEM; 139 140 if (addr) { 141 addr = PAGE_ALIGN(addr); 142 vma = find_vma(mm, addr); 143 if (end - len >= addr && 144 (!vma || addr + len <= vma->vm_start)) 145 return addr; 146 } 147 148 info.flags = 0; 149 info.length = len; 150 info.low_limit = begin; 151 info.high_limit = end; 152 info.align_mask = 0; 153 info.align_offset = pgoff << PAGE_SHIFT; 154 if (filp) { 155 info.align_mask = get_align_mask(); 156 info.align_offset += get_align_bits(); 157 } 158 return vm_unmapped_area(&info); 159 } 160 161 unsigned long 162 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 163 const unsigned long len, const unsigned long pgoff, 164 const unsigned long flags) 165 { 166 struct vm_area_struct *vma; 167 struct mm_struct *mm = current->mm; 168 unsigned long addr = addr0; 169 struct vm_unmapped_area_info info; 170 171 /* requested length too big for entire address space */ 172 if (len > TASK_SIZE) 173 return -ENOMEM; 174 175 if (flags & MAP_FIXED) 176 return addr; 177 178 /* for MAP_32BIT mappings we force the legacy mmap base */ 179 if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT)) 180 goto bottomup; 181 182 /* requesting a specific address */ 183 if (addr) { 184 addr = PAGE_ALIGN(addr); 185 vma = find_vma(mm, addr); 186 if (TASK_SIZE - len >= addr && 187 (!vma || addr + len <= vma->vm_start)) 188 return addr; 189 } 190 191 info.flags = VM_UNMAPPED_AREA_TOPDOWN; 192 info.length = len; 193 info.low_limit = PAGE_SIZE; 194 info.high_limit = mm->mmap_base; 195 info.align_mask = 0; 196 info.align_offset = pgoff << PAGE_SHIFT; 197 if (filp) { 198 info.align_mask = get_align_mask(); 199 info.align_offset += get_align_bits(); 200 } 201 addr = vm_unmapped_area(&info); 202 if (!(addr & ~PAGE_MASK)) 203 return addr; 204 VM_BUG_ON(addr != -ENOMEM); 205 206 bottomup: 207 /* 208 * A failed mmap() very likely causes application failure, 209 * so fall back to the bottom-up function here. This scenario 210 * can happen with large stack limits and large mmap() 211 * allocations. 212 */ 213 return arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 214 } 215