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 #ifdef CONFIG_UACCESS_MEMCPY
  13 #include <asm/unaligned.h>
  14
  15 static __always_inline int
  16 __get_user_fn(size_t size, const void __user *from, void *to)
  17 {
  18         BUILD_BUG_ON(!__builtin_constant_p(size));
  19
  20         switch (size) {
  21         case 1:
  22                 *(u8 *)to = *((u8 __force *)from);
  23                 return 0;
  24         case 2:
  25                 *(u16 *)to = get_unaligned((u16 __force *)from);
  26                 return 0;
  27         case 4:
  28                 *(u32 *)to = get_unaligned((u32 __force *)from);
  29                 return 0;
  30         case 8:
  31                 *(u64 *)to = get_unaligned((u64 __force *)from);
  32                 return 0;
  33         default:
  34                 BUILD_BUG();
  35                 return 0;
  36         }
  37
  38 }
  39 #define __get_user_fn(sz, u, k) __get_user_fn(sz, u, k)
  40
  41 static __always_inline int
  42 __put_user_fn(size_t size, void __user *to, void *from)
  43 {
  44         BUILD_BUG_ON(!__builtin_constant_p(size));
  45
  46         switch (size) {
  47         case 1:
  48                 *(u8 __force *)to = *(u8 *)from;
  49                 return 0;
  50         case 2:
  51                 put_unaligned(*(u16 *)from, (u16 __force *)to);
  52                 return 0;
  53         case 4:
  54                 put_unaligned(*(u32 *)from, (u32 __force *)to);
  55                 return 0;
  56         case 8:
  57                 put_unaligned(*(u64 *)from, (u64 __force *)to);
  58                 return 0;
  59         default:
  60                 BUILD_BUG();
  61                 return 0;
  62         }
  63 }
  64 #define __put_user_fn(sz, u, k) __put_user_fn(sz, u, k)
  65
  66 #define __get_kernel_nofault(dst, src, type, err_label)                 \
  67 do {                                                                    \
  68         *((type *)dst) = get_unaligned((type *)(src));                  \
  69         if (0) /* make sure the label looks used to the compiler */     \
  70                 goto err_label;                                         \
  71 } while (0)
  72
  73 #define __put_kernel_nofault(dst, src, type, err_label)                 \
  74 do {                                                                    \
  75         put_unaligned(*((type *)src), (type *)(dst));                   \
  76         if (0) /* make sure the label looks used to the compiler */     \
  77                 goto err_label;                                         \
  78 } while (0)
  79
  80 #define HAVE_GET_KERNEL_NOFAULT 1
  81
  82 static inline __must_check unsigned long
  83 raw_copy_from_user(void *to, const void __user * from, unsigned long n)
  84 {
  85         memcpy(to, (const void __force *)from, n);
  86         return 0;
  87 }
  88
  89 static inline __must_check unsigned long
  90 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
  91 {
  92         memcpy((void __force *)to, from, n);
  93         return 0;
  94 }
  95 #define INLINE_COPY_FROM_USER
  96 #define INLINE_COPY_TO_USER
  97 #endif /* CONFIG_UACCESS_MEMCPY */
  98
  99 #ifdef CONFIG_SET_FS
 100 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
 101
 102 #ifndef KERNEL_DS
 103 #define KERNEL_DS       MAKE_MM_SEG(~0UL)
 104 #endif
 105
 106 #ifndef USER_DS
 107 #define USER_DS         MAKE_MM_SEG(TASK_SIZE - 1)
 108 #endif
 109
 110 #ifndef get_fs
 111 #define get_fs()        (current_thread_info()->addr_limit)
 112
 113 static inline void set_fs(mm_segment_t fs)
 114 {
 115         current_thread_info()->addr_limit = fs;
 116 }
 117 #endif
 118
 119 #ifndef uaccess_kernel
 120 #define uaccess_kernel() (get_fs().seg == KERNEL_DS.seg)
 121 #endif
 122 #endif /* CONFIG_SET_FS */
 123
 124 #define access_ok(addr, size) __access_ok((unsigned long)(addr),(size))
 125
 126 /*
 127  * The architecture should really override this if possible, at least
 128  * doing a check on the get_fs()
 129  */
 130 #ifndef __access_ok
 131 static inline int __access_ok(unsigned long addr, unsigned long size)
 132 {
 133         return 1;
 134 }
 135 #endif
 136
 137 /*
 138  * These are the main single-value transfer routines.  They automatically
 139  * use the right size if we just have the right pointer type.
 140  * This version just falls back to copy_{from,to}_user, which should
 141  * provide a fast-path for small values.
 142  */
 143 #define __put_user(x, ptr) \
 144 ({                                                              \
 145         __typeof__(*(ptr)) __x = (x);                           \
 146         int __pu_err = -EFAULT;                                 \
 147         __chk_user_ptr(ptr);                                    \
 148         switch (sizeof (*(ptr))) {                              \
 149         case 1:                                                 \
 150         case 2:                                                 \
 151         case 4:                                                 \
 152         case 8:                                                 \
 153                 __pu_err = __put_user_fn(sizeof (*(ptr)),       \
 154                                          ptr, &__x);            \
 155                 break;                                          \
 156         default:                                                \
 157                 __put_user_bad();                               \
 158                 break;                                          \
 159          }                                                      \
 160         __pu_err;                                               \
 161 })
 162
 163 #define put_user(x, ptr)                                        \
 164 ({                                                              \
 165         void __user *__p = (ptr);                               \
 166         might_fault();                                          \
 167         access_ok(__p, sizeof(*ptr)) ?          \
 168                 __put_user((x), ((__typeof__(*(ptr)) __user *)__p)) :   \
 169                 -EFAULT;                                        \
 170 })
 171
 172 #ifndef __put_user_fn
 173
 174 static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
 175 {
 176         return unlikely(raw_copy_to_user(ptr, x, size)) ? -EFAULT : 0;
 177 }
 178
 179 #define __put_user_fn(sz, u, k) __put_user_fn(sz, u, k)
 180
 181 #endif
 182
 183 extern int __put_user_bad(void) __attribute__((noreturn));
 184
 185 #define __get_user(x, ptr)                                      \
 186 ({                                                              \
 187         int __gu_err = -EFAULT;                                 \
 188         __chk_user_ptr(ptr);                                    \
 189         switch (sizeof(*(ptr))) {                               \
 190         case 1: {                                               \
 191                 unsigned char __x = 0;                          \
 192                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 193                                          ptr, &__x);            \
 194                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 195                 break;                                          \
 196         };                                                      \
 197         case 2: {                                               \
 198                 unsigned short __x = 0;                         \
 199                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 200                                          ptr, &__x);            \
 201                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 202                 break;                                          \
 203         };                                                      \
 204         case 4: {                                               \
 205                 unsigned int __x = 0;                           \
 206                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 207                                          ptr, &__x);            \
 208                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 209                 break;                                          \
 210         };                                                      \
 211         case 8: {                                               \
 212                 unsigned long long __x = 0;                     \
 213                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 214                                          ptr, &__x);            \
 215                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 216                 break;                                          \
 217         };                                                      \
 218         default:                                                \
 219                 __get_user_bad();                               \
 220                 break;                                          \
 221         }                                                       \
 222         __gu_err;                                               \
 223 })
 224
 225 #define get_user(x, ptr)                                        \
 226 ({                                                              \
 227         const void __user *__p = (ptr);                         \
 228         might_fault();                                          \
 229         access_ok(__p, sizeof(*ptr)) ?          \
 230                 __get_user((x), (__typeof__(*(ptr)) __user *)__p) :\
 231                 ((x) = (__typeof__(*(ptr)))0,-EFAULT);          \
 232 })
 233
 234 #ifndef __get_user_fn
 235 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
 236 {
 237         return unlikely(raw_copy_from_user(x, ptr, size)) ? -EFAULT : 0;
 238 }
 239
 240 #define __get_user_fn(sz, u, k) __get_user_fn(sz, u, k)
 241
 242 #endif
 243
 244 extern int __get_user_bad(void) __attribute__((noreturn));
 245
 246 /*
 247  * Copy a null terminated string from userspace.
 248  */
 249 #ifndef __strncpy_from_user
 250 static inline long
 251 __strncpy_from_user(char *dst, const char __user *src, long count)
 252 {
 253         char *tmp;
 254         strncpy(dst, (const char __force *)src, count);
 255         for (tmp = dst; *tmp && count > 0; tmp++, count--)
 256                 ;
 257         return (tmp - dst);
 258 }
 259 #endif
 260
 261 static inline long
 262 strncpy_from_user(char *dst, const char __user *src, long count)
 263 {
 264         if (!access_ok(src, 1))
 265                 return -EFAULT;
 266         return __strncpy_from_user(dst, src, count);
 267 }
 268
 269 /*
 270  * Return the size of a string (including the ending 0)
 271  *
 272  * Return 0 on exception, a value greater than N if too long
 273  */
 274 #ifndef __strnlen_user
 275 #define __strnlen_user(s, n) (strnlen((s), (n)) + 1)
 276 #endif
 277
 278 /*
 279  * Unlike strnlen, strnlen_user includes the nul terminator in
 280  * its returned count. Callers should check for a returned value
 281  * greater than N as an indication the string is too long.
 282  */
 283 static inline long strnlen_user(const char __user *src, long n)
 284 {
 285         if (!access_ok(src, 1))
 286                 return 0;
 287         return __strnlen_user(src, n);
 288 }
 289
 290 /*
 291  * Zero Userspace
 292  */
 293 #ifndef __clear_user
 294 static inline __must_check unsigned long
 295 __clear_user(void __user *to, unsigned long n)
 296 {
 297         memset((void __force *)to, 0, n);
 298         return 0;
 299 }
 300 #endif
 301
 302 static inline __must_check unsigned long
 303 clear_user(void __user *to, unsigned long n)
 304 {
 305         might_fault();
 306         if (!access_ok(to, n))
 307                 return n;
 308
 309         return __clear_user(to, n);
 310 }
 311
 312 #include <asm/extable.h>
 313
 314 #endif /* __ASM_GENERIC_UACCESS_H */