include/asm-generic/uaccess.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __ASM_GENERIC_UACCESS_H
   3 #define __ASM_GENERIC_UACCESS_H
   4
   5 /*
   6  * User space memory access functions, these should work
   7  * on any machine that has kernel and user data in the same
   8  * address space, e.g. all NOMMU machines.
   9  */
  10 #include <linux/string.h>
  11
  12 #include <asm/segment.h>
  13
  14 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  15
  16 #ifndef KERNEL_DS
  17 #define KERNEL_DS       MAKE_MM_SEG(~0UL)
  18 #endif
  19
  20 #ifndef USER_DS
  21 #define USER_DS         MAKE_MM_SEG(TASK_SIZE - 1)
  22 #endif
  23
  24 #ifndef get_fs
  25 #define get_ds()        (KERNEL_DS)
  26 #define get_fs()        (current_thread_info()->addr_limit)
  27
  28 static inline void set_fs(mm_segment_t fs)
  29 {
  30         current_thread_info()->addr_limit = fs;
  31 }
  32 #endif
  33
  34 #ifndef segment_eq
  35 #define segment_eq(a, b) ((a).seg == (b).seg)
  36 #endif
  37
  38 #define access_ok(type, addr, size) __access_ok((unsigned long)(addr),(size))
  39
  40 /*
  41  * The architecture should really override this if possible, at least
  42  * doing a check on the get_fs()
  43  */
  44 #ifndef __access_ok
  45 static inline int __access_ok(unsigned long addr, unsigned long size)
  46 {
  47         return 1;
  48 }
  49 #endif
  50
  51 /*
  52  * These are the main single-value transfer routines.  They automatically
  53  * use the right size if we just have the right pointer type.
  54  * This version just falls back to copy_{from,to}_user, which should
  55  * provide a fast-path for small values.
  56  */
  57 #define __put_user(x, ptr) \
  58 ({                                                              \
  59         __typeof__(*(ptr)) __x = (x);                           \
  60         int __pu_err = -EFAULT;                                 \
  61         __chk_user_ptr(ptr);                                    \
  62         switch (sizeof (*(ptr))) {                              \
  63         case 1:                                                 \
  64         case 2:                                                 \
  65         case 4:                                                 \
  66         case 8:                                                 \
  67                 __pu_err = __put_user_fn(sizeof (*(ptr)),       \
  68                                          ptr, &__x);            \
  69                 break;                                          \
  70         default:                                                \
  71                 __put_user_bad();                               \
  72                 break;                                          \
  73          }                                                      \
  74         __pu_err;                                               \
  75 })
  76
  77 #define put_user(x, ptr)                                        \
  78 ({                                                              \
  79         void __user *__p = (ptr);                               \
  80         might_fault();                                          \
  81         access_ok(VERIFY_WRITE, __p, sizeof(*ptr)) ?            \
  82                 __put_user((x), ((__typeof__(*(ptr)) __user *)__p)) :   \
  83                 -EFAULT;                                        \
  84 })
  85
  86 #ifndef __put_user_fn
  87
  88 static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
  89 {
  90         return unlikely(raw_copy_to_user(ptr, x, size)) ? -EFAULT : 0;
  91 }
  92
  93 #define __put_user_fn(sz, u, k) __put_user_fn(sz, u, k)
  94
  95 #endif
  96
  97 extern int __put_user_bad(void) __attribute__((noreturn));
  98
  99 #define __get_user(x, ptr)                                      \
 100 ({                                                              \
 101         int __gu_err = -EFAULT;                                 \
 102         __chk_user_ptr(ptr);                                    \
 103         switch (sizeof(*(ptr))) {                               \
 104         case 1: {                                               \
 105                 unsigned char __x = 0;                          \
 106                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 107                                          ptr, &__x);            \
 108                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 109                 break;                                          \
 110         };                                                      \
 111         case 2: {                                               \
 112                 unsigned short __x = 0;                         \
 113                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 114                                          ptr, &__x);            \
 115                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 116                 break;                                          \
 117         };                                                      \
 118         case 4: {                                               \
 119                 unsigned int __x = 0;                           \
 120                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 121                                          ptr, &__x);            \
 122                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 123                 break;                                          \
 124         };                                                      \
 125         case 8: {                                               \
 126                 unsigned long long __x = 0;                     \
 127                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 128                                          ptr, &__x);            \
 129                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 130                 break;                                          \
 131         };                                                      \
 132         default:                                                \
 133                 __get_user_bad();                               \
 134                 break;                                          \
 135         }                                                       \
 136         __gu_err;                                               \
 137 })
 138
 139 #define get_user(x, ptr)                                        \
 140 ({                                                              \
 141         const void __user *__p = (ptr);                         \
 142         might_fault();                                          \
 143         access_ok(VERIFY_READ, __p, sizeof(*ptr)) ?             \
 144                 __get_user((x), (__typeof__(*(ptr)) __user *)__p) :\
 145                 ((x) = (__typeof__(*(ptr)))0,-EFAULT);          \
 146 })
 147
 148 #ifndef __get_user_fn
 149 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
 150 {
 151         return unlikely(raw_copy_from_user(x, ptr, size)) ? -EFAULT : 0;
 152 }
 153
 154 #define __get_user_fn(sz, u, k) __get_user_fn(sz, u, k)
 155
 156 #endif
 157
 158 extern int __get_user_bad(void) __attribute__((noreturn));
 159
 160 /*
 161  * Copy a null terminated string from userspace.
 162  */
 163 #ifndef __strncpy_from_user
 164 static inline long
 165 __strncpy_from_user(char *dst, const char __user *src, long count)
 166 {
 167         char *tmp;
 168         strncpy(dst, (const char __force *)src, count);
 169         for (tmp = dst; *tmp && count > 0; tmp++, count--)
 170                 ;
 171         return (tmp - dst);
 172 }
 173 #endif
 174
 175 static inline long
 176 strncpy_from_user(char *dst, const char __user *src, long count)
 177 {
 178         if (!access_ok(VERIFY_READ, src, 1))
 179                 return -EFAULT;
 180         return __strncpy_from_user(dst, src, count);
 181 }
 182
 183 /*
 184  * Return the size of a string (including the ending 0)
 185  *
 186  * Return 0 on exception, a value greater than N if too long
 187  */
 188 #ifndef __strnlen_user
 189 #define __strnlen_user(s, n) (strnlen((s), (n)) + 1)
 190 #endif
 191
 192 /*
 193  * Unlike strnlen, strnlen_user includes the nul terminator in
 194  * its returned count. Callers should check for a returned value
 195  * greater than N as an indication the string is too long.
 196  */
 197 static inline long strnlen_user(const char __user *src, long n)
 198 {
 199         if (!access_ok(VERIFY_READ, src, 1))
 200                 return 0;
 201         return __strnlen_user(src, n);
 202 }
 203
 204 /*
 205  * Zero Userspace
 206  */
 207 #ifndef __clear_user
 208 static inline __must_check unsigned long
 209 __clear_user(void __user *to, unsigned long n)
 210 {
 211         memset((void __force *)to, 0, n);
 212         return 0;
 213 }
 214 #endif
 215
 216 static inline __must_check unsigned long
 217 clear_user(void __user *to, unsigned long n)
 218 {
 219         might_fault();
 220         if (!access_ok(VERIFY_WRITE, to, n))
 221                 return n;
 222
 223         return __clear_user(to, n);
 224 }
 225
 226 #include <asm/extable.h>
 227
 228 #endif /* __ASM_GENERIC_UACCESS_H */