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