arch/x86/lib/usercopy_64.c

   1 /*
   2  * User address space access functions.
   3  *
   4  * Copyright 1997 Andi Kleen <ak@muc.de>
   5  * Copyright 1997 Linus Torvalds
   6  * Copyright 2002 Andi Kleen <ak@suse.de>
   7  */
   8 #include <linux/module.h>
   9 #include <asm/uaccess.h>
  10
  11 /*
  12  * Copy a null terminated string from userspace.
  13  */
  14
  15 #define __do_strncpy_from_user(dst,src,count,res)                          \
  16 do {                                                                       \
  17         long __d0, __d1, __d2;                                             \
  18         might_fault();                                                     \
  19         __asm__ __volatile__(                                              \
  20                 "       testq %1,%1\n"                                     \
  21                 "       jz 2f\n"                                           \
  22                 "0:     lodsb\n"                                           \
  23                 "       stosb\n"                                           \
  24                 "       testb %%al,%%al\n"                                 \
  25                 "       jz 1f\n"                                           \
  26                 "       decq %1\n"                                         \
  27                 "       jnz 0b\n"                                          \
  28                 "1:     subq %1,%0\n"                                      \
  29                 "2:\n"                                                     \
  30                 ".section .fixup,\"ax\"\n"                                 \
  31                 "3:     movq %5,%0\n"                                      \
  32                 "       jmp 2b\n"                                          \
  33                 ".previous\n"                                              \
  34                 _ASM_EXTABLE(0b,3b)                                        \
  35                 : "=&r"(res), "=&c"(count), "=&a" (__d0), "=&S" (__d1),    \
  36                   "=&D" (__d2)                                             \
  37                 : "i"(-EFAULT), "0"(count), "1"(count), "3"(src), "4"(dst) \
  38                 : "memory");                                               \
  39 } while (0)
  40
  41 long
  42 __strncpy_from_user(char *dst, const char __user *src, long count)
  43 {
  44         long res;
  45         __do_strncpy_from_user(dst, src, count, res);
  46         return res;
  47 }
  48 EXPORT_SYMBOL(__strncpy_from_user);
  49
  50 long
  51 strncpy_from_user(char *dst, const char __user *src, long count)
  52 {
  53         long res = -EFAULT;
  54         if (access_ok(VERIFY_READ, src, 1))
  55                 return __strncpy_from_user(dst, src, count);
  56         return res;
  57 }
  58 EXPORT_SYMBOL(strncpy_from_user);
  59
  60 /*
  61  * Zero Userspace
  62  */
  63
  64 unsigned long __clear_user(void __user *addr, unsigned long size)
  65 {
  66         long __d0;
  67         might_fault();
  68         /* no memory constraint because it doesn't change any memory gcc knows
  69            about */
  70         asm volatile(
  71                 "       testq  %[size8],%[size8]\n"
  72                 "       jz     4f\n"
  73                 "0:     movq %[zero],(%[dst])\n"
  74                 "       addq   %[eight],%[dst]\n"
  75                 "       decl %%ecx ; jnz   0b\n"
  76                 "4:     movq  %[size1],%%rcx\n"
  77                 "       testl %%ecx,%%ecx\n"
  78                 "       jz     2f\n"
  79                 "1:     movb   %b[zero],(%[dst])\n"
  80                 "       incq   %[dst]\n"
  81                 "       decl %%ecx ; jnz  1b\n"
  82                 "2:\n"
  83                 ".section .fixup,\"ax\"\n"
  84                 "3:     lea 0(%[size1],%[size8],8),%[size8]\n"
  85                 "       jmp 2b\n"
  86                 ".previous\n"
  87                 _ASM_EXTABLE(0b,3b)
  88                 _ASM_EXTABLE(1b,2b)
  89                 : [size8] "=&c"(size), [dst] "=&D" (__d0)
  90                 : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr),
  91                   [zero] "r" (0UL), [eight] "r" (8UL));
  92         return size;
  93 }
  94 EXPORT_SYMBOL(__clear_user);
  95
  96 unsigned long clear_user(void __user *to, unsigned long n)
  97 {
  98         if (access_ok(VERIFY_WRITE, to, n))
  99                 return __clear_user(to, n);
 100         return n;
 101 }
 102 EXPORT_SYMBOL(clear_user);
 103
 104 /*
 105  * Return the size of a string (including the ending 0)
 106  *
 107  * Return 0 on exception, a value greater than N if too long
 108  */
 109
 110 long __strnlen_user(const char __user *s, long n)
 111 {
 112         long res = 0;
 113         char c;
 114
 115         while (1) {
 116                 if (res>n)
 117                         return n+1;
 118                 if (__get_user(c, s))
 119                         return 0;
 120                 if (!c)
 121                         return res+1;
 122                 res++;
 123                 s++;
 124         }
 125 }
 126 EXPORT_SYMBOL(__strnlen_user);
 127
 128 long strnlen_user(const char __user *s, long n)
 129 {
 130         if (!access_ok(VERIFY_READ, s, n))
 131                 return 0;
 132         return __strnlen_user(s, n);
 133 }
 134 EXPORT_SYMBOL(strnlen_user);
 135
 136 long strlen_user(const char __user *s)
 137 {
 138         long res = 0;
 139         char c;
 140
 141         for (;;) {
 142                 if (get_user(c, s))
 143                         return 0;
 144                 if (!c)
 145                         return res+1;
 146                 res++;
 147                 s++;
 148         }
 149 }
 150 EXPORT_SYMBOL(strlen_user);
 151
 152 unsigned long copy_in_user(void __user *to, const void __user *from, unsigned len)
 153 {
 154         if (access_ok(VERIFY_WRITE, to, len) && access_ok(VERIFY_READ, from, len)) {
 155                 return copy_user_generic((__force void *)to, (__force void *)from, len);
 156         }
 157         return len;
 158 }
 159 EXPORT_SYMBOL(copy_in_user);
 160
 161 /*
 162  * Try to copy last bytes and clear the rest if needed.
 163  * Since protection fault in copy_from/to_user is not a normal situation,
 164  * it is not necessary to optimize tail handling.
 165  */
 166 unsigned long
 167 copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest)
 168 {
 169         char c;
 170         unsigned zero_len;
 171
 172         for (; len; --len) {
 173                 if (__get_user_nocheck(c, from++, sizeof(char)))
 174                         break;
 175                 if (__put_user_nocheck(c, to++, sizeof(char)))
 176                         break;
 177         }
 178
 179         for (c = 0, zero_len = len; zerorest && zero_len; --zero_len)
 180                 if (__put_user_nocheck(c, to++, sizeof(char)))
 181                         break;
 182         return len;
 183 }