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