arch/x86/include/asm/uaccess.h

   1 #ifndef _ASM_X86_UACCESS_H
   2 #define _ASM_X86_UACCESS_H
   3 /*
   4  * User space memory access functions
   5  */
   6 #include <linux/errno.h>
   7 #include <linux/compiler.h>
   8 #include <linux/kasan-checks.h>
   9 #include <linux/thread_info.h>
  10 #include <linux/string.h>
  11 #include <asm/asm.h>
  12 #include <asm/page.h>
  13 #include <asm/smap.h>
  14
  15 #define VERIFY_READ 0
  16 #define VERIFY_WRITE 1
  17
  18 /*
  19  * The fs value determines whether argument validity checking should be
  20  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  21  * get_fs() == KERNEL_DS, checking is bypassed.
  22  *
  23  * For historical reasons, these macros are grossly misnamed.
  24  */
  25
  26 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  27
  28 #define KERNEL_DS       MAKE_MM_SEG(-1UL)
  29 #define USER_DS         MAKE_MM_SEG(TASK_SIZE_MAX)
  30
  31 #define get_ds()        (KERNEL_DS)
  32 #define get_fs()        (current->thread.addr_limit)
  33 #define set_fs(x)       (current->thread.addr_limit = (x))
  34
  35 #define segment_eq(a, b)        ((a).seg == (b).seg)
  36
  37 #define user_addr_max() (current->thread.addr_limit.seg)
  38 #define __addr_ok(addr)         \
  39         ((unsigned long __force)(addr) < user_addr_max())
  40
  41 /*
  42  * Test whether a block of memory is a valid user space address.
  43  * Returns 0 if the range is valid, nonzero otherwise.
  44  */
  45 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
  46 {
  47         /*
  48          * If we have used "sizeof()" for the size,
  49          * we know it won't overflow the limit (but
  50          * it might overflow the 'addr', so it's
  51          * important to subtract the size from the
  52          * limit, not add it to the address).
  53          */
  54         if (__builtin_constant_p(size))
  55                 return unlikely(addr > limit - size);
  56
  57         /* Arbitrary sizes? Be careful about overflow */
  58         addr += size;
  59         if (unlikely(addr < size))
  60                 return true;
  61         return unlikely(addr > limit);
  62 }
  63
  64 #define __range_not_ok(addr, size, limit)                               \
  65 ({                                                                      \
  66         __chk_user_ptr(addr);                                           \
  67         __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
  68 })
  69
  70 /**
  71  * access_ok: - Checks if a user space pointer is valid
  72  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
  73  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
  74  *        to write to a block, it is always safe to read from it.
  75  * @addr: User space pointer to start of block to check
  76  * @size: Size of block to check
  77  *
  78  * Context: User context only. This function may sleep if pagefaults are
  79  *          enabled.
  80  *
  81  * Checks if a pointer to a block of memory in user space is valid.
  82  *
  83  * Returns true (nonzero) if the memory block may be valid, false (zero)
  84  * if it is definitely invalid.
  85  *
  86  * Note that, depending on architecture, this function probably just
  87  * checks that the pointer is in the user space range - after calling
  88  * this function, memory access functions may still return -EFAULT.
  89  */
  90 #define access_ok(type, addr, size) \
  91         likely(!__range_not_ok(addr, size, user_addr_max()))
  92
  93 /*
  94  * The exception table consists of triples of addresses relative to the
  95  * exception table entry itself. The first address is of an instruction
  96  * that is allowed to fault, the second is the target at which the program
  97  * should continue. The third is a handler function to deal with the fault
  98  * caused by the instruction in the first field.
  99  *
 100  * All the routines below use bits of fixup code that are out of line
 101  * with the main instruction path.  This means when everything is well,
 102  * we don't even have to jump over them.  Further, they do not intrude
 103  * on our cache or tlb entries.
 104  */
 105
 106 struct exception_table_entry {
 107         int insn, fixup, handler;
 108 };
 109
 110 #define ARCH_HAS_RELATIVE_EXTABLE
 111
 112 #define swap_ex_entry_fixup(a, b, tmp, delta)                   \
 113         do {                                                    \
 114                 (a)->fixup = (b)->fixup + (delta);              \
 115                 (b)->fixup = (tmp).fixup - (delta);             \
 116                 (a)->handler = (b)->handler + (delta);          \
 117                 (b)->handler = (tmp).handler - (delta);         \
 118         } while (0)
 119
 120 extern int fixup_exception(struct pt_regs *regs, int trapnr);
 121 extern bool ex_has_fault_handler(unsigned long ip);
 122 extern void early_fixup_exception(struct pt_regs *regs, int trapnr);
 123
 124 /*
 125  * These are the main single-value transfer routines.  They automatically
 126  * use the right size if we just have the right pointer type.
 127  *
 128  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 129  * and yet we don't want to do any pointers, because that is too much
 130  * of a performance impact. Thus we have a few rather ugly macros here,
 131  * and hide all the ugliness from the user.
 132  *
 133  * The "__xxx" versions of the user access functions are versions that
 134  * do not verify the address space, that must have been done previously
 135  * with a separate "access_ok()" call (this is used when we do multiple
 136  * accesses to the same area of user memory).
 137  */
 138
 139 extern int __get_user_1(void);
 140 extern int __get_user_2(void);
 141 extern int __get_user_4(void);
 142 extern int __get_user_8(void);
 143 extern int __get_user_bad(void);
 144
 145 #define __uaccess_begin() stac()
 146 #define __uaccess_end()   clac()
 147
 148 /*
 149  * This is a type: either unsigned long, if the argument fits into
 150  * that type, or otherwise unsigned long long.
 151  */
 152 #define __inttype(x) \
 153 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 154
 155 /**
 156  * get_user: - Get a simple variable from user space.
 157  * @x:   Variable to store result.
 158  * @ptr: Source address, in user space.
 159  *
 160  * Context: User context only. This function may sleep if pagefaults are
 161  *          enabled.
 162  *
 163  * This macro copies a single simple variable from user space to kernel
 164  * space.  It supports simple types like char and int, but not larger
 165  * data types like structures or arrays.
 166  *
 167  * @ptr must have pointer-to-simple-variable type, and the result of
 168  * dereferencing @ptr must be assignable to @x without a cast.
 169  *
 170  * Returns zero on success, or -EFAULT on error.
 171  * On error, the variable @x is set to zero.
 172  */
 173 /*
 174  * Careful: we have to cast the result to the type of the pointer
 175  * for sign reasons.
 176  *
 177  * The use of _ASM_DX as the register specifier is a bit of a
 178  * simplification, as gcc only cares about it as the starting point
 179  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 180  * (%ecx being the next register in gcc's x86 register sequence), and
 181  * %rdx on 64 bits.
 182  *
 183  * Clang/LLVM cares about the size of the register, but still wants
 184  * the base register for something that ends up being a pair.
 185  */
 186 #define get_user(x, ptr)                                                \
 187 ({                                                                      \
 188         int __ret_gu;                                                   \
 189         register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 190         register void *__sp asm(_ASM_SP);                               \
 191         __chk_user_ptr(ptr);                                            \
 192         might_fault();                                                  \
 193         asm volatile("call __get_user_%P4"                              \
 194                      : "=a" (__ret_gu), "=r" (__val_gu), "+r" (__sp)    \
 195                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 196         (x) = (__force __typeof__(*(ptr))) __val_gu;                    \
 197         __builtin_expect(__ret_gu, 0);                                  \
 198 })
 199
 200 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 201         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 202                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 203
 204
 205
 206 #ifdef CONFIG_X86_32
 207 #define __put_user_asm_u64(x, addr, err, errret)                        \
 208         asm volatile("\n"                                               \
 209                      "1:        movl %%eax,0(%2)\n"                     \
 210                      "2:        movl %%edx,4(%2)\n"                     \
 211                      "3:"                                               \
 212                      ".section .fixup,\"ax\"\n"                         \
 213                      "4:        movl %3,%0\n"                           \
 214                      "  jmp 3b\n"                                       \
 215                      ".previous\n"                                      \
 216                      _ASM_EXTABLE(1b, 4b)                               \
 217                      _ASM_EXTABLE(2b, 4b)                               \
 218                      : "=r" (err)                                       \
 219                      : "A" (x), "r" (addr), "i" (errret), "0" (err))
 220
 221 #define __put_user_asm_ex_u64(x, addr)                                  \
 222         asm volatile("\n"                                               \
 223                      "1:        movl %%eax,0(%1)\n"                     \
 224                      "2:        movl %%edx,4(%1)\n"                     \
 225                      "3:"                                               \
 226                      _ASM_EXTABLE_EX(1b, 2b)                            \
 227                      _ASM_EXTABLE_EX(2b, 3b)                            \
 228                      : : "A" (x), "r" (addr))
 229
 230 #define __put_user_x8(x, ptr, __ret_pu)                         \
 231         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 232                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 233 #else
 234 #define __put_user_asm_u64(x, ptr, retval, errret) \
 235         __put_user_asm(x, ptr, retval, "q", "", "er", errret)
 236 #define __put_user_asm_ex_u64(x, addr)  \
 237         __put_user_asm_ex(x, addr, "q", "", "er")
 238 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 239 #endif
 240
 241 extern void __put_user_bad(void);
 242
 243 /*
 244  * Strange magic calling convention: pointer in %ecx,
 245  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 246  */
 247 extern void __put_user_1(void);
 248 extern void __put_user_2(void);
 249 extern void __put_user_4(void);
 250 extern void __put_user_8(void);
 251
 252 /**
 253  * put_user: - Write a simple value into user space.
 254  * @x:   Value to copy to user space.
 255  * @ptr: Destination address, in user space.
 256  *
 257  * Context: User context only. This function may sleep if pagefaults are
 258  *          enabled.
 259  *
 260  * This macro copies a single simple value from kernel space to user
 261  * space.  It supports simple types like char and int, but not larger
 262  * data types like structures or arrays.
 263  *
 264  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 265  * to the result of dereferencing @ptr.
 266  *
 267  * Returns zero on success, or -EFAULT on error.
 268  */
 269 #define put_user(x, ptr)                                        \
 270 ({                                                              \
 271         int __ret_pu;                                           \
 272         __typeof__(*(ptr)) __pu_val;                            \
 273         __chk_user_ptr(ptr);                                    \
 274         might_fault();                                          \
 275         __pu_val = x;                                           \
 276         switch (sizeof(*(ptr))) {                               \
 277         case 1:                                                 \
 278                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 279                 break;                                          \
 280         case 2:                                                 \
 281                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 282                 break;                                          \
 283         case 4:                                                 \
 284                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 285                 break;                                          \
 286         case 8:                                                 \
 287                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 288                 break;                                          \
 289         default:                                                \
 290                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 291                 break;                                          \
 292         }                                                       \
 293         __builtin_expect(__ret_pu, 0);                          \
 294 })
 295
 296 #define __put_user_size(x, ptr, size, retval, errret)                   \
 297 do {                                                                    \
 298         retval = 0;                                                     \
 299         __chk_user_ptr(ptr);                                            \
 300         switch (size) {                                                 \
 301         case 1:                                                         \
 302                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 303                 break;                                                  \
 304         case 2:                                                         \
 305                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 306                 break;                                                  \
 307         case 4:                                                         \
 308                 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
 309                 break;                                                  \
 310         case 8:                                                         \
 311                 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,  \
 312                                    errret);                             \
 313                 break;                                                  \
 314         default:                                                        \
 315                 __put_user_bad();                                       \
 316         }                                                               \
 317 } while (0)
 318
 319 /*
 320  * This doesn't do __uaccess_begin/end - the exception handling
 321  * around it must do that.
 322  */
 323 #define __put_user_size_ex(x, ptr, size)                                \
 324 do {                                                                    \
 325         __chk_user_ptr(ptr);                                            \
 326         switch (size) {                                                 \
 327         case 1:                                                         \
 328                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 329                 break;                                                  \
 330         case 2:                                                         \
 331                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 332                 break;                                                  \
 333         case 4:                                                         \
 334                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 335                 break;                                                  \
 336         case 8:                                                         \
 337                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 338                 break;                                                  \
 339         default:                                                        \
 340                 __put_user_bad();                                       \
 341         }                                                               \
 342 } while (0)
 343
 344 #ifdef CONFIG_X86_32
 345 #define __get_user_asm_u64(x, ptr, retval, errret)                      \
 346 ({                                                                      \
 347         __typeof__(ptr) __ptr = (ptr);                                  \
 348         asm volatile(ASM_STAC "\n"                                      \
 349                      "1:        movl %2,%%eax\n"                        \
 350                      "2:        movl %3,%%edx\n"                        \
 351                      "3: " ASM_CLAC "\n"                                \
 352                      ".section .fixup,\"ax\"\n"                         \
 353                      "4:        mov %4,%0\n"                            \
 354                      "  xorl %%eax,%%eax\n"                             \
 355                      "  xorl %%edx,%%edx\n"                             \
 356                      "  jmp 3b\n"                                       \
 357                      ".previous\n"                                      \
 358                      _ASM_EXTABLE(1b, 4b)                               \
 359                      _ASM_EXTABLE(2b, 4b)                               \
 360                      : "=r" (retval), "=A"(x)                           \
 361                      : "m" (__m(__ptr)), "m" __m(((u32 *)(__ptr)) + 1), \
 362                        "i" (errret), "0" (retval));                     \
 363 })
 364
 365 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 366 #else
 367 #define __get_user_asm_u64(x, ptr, retval, errret) \
 368          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 369 #define __get_user_asm_ex_u64(x, ptr) \
 370          __get_user_asm_ex(x, ptr, "q", "", "=r")
 371 #endif
 372
 373 #define __get_user_size(x, ptr, size, retval, errret)                   \
 374 do {                                                                    \
 375         retval = 0;                                                     \
 376         __chk_user_ptr(ptr);                                            \
 377         switch (size) {                                                 \
 378         case 1:                                                         \
 379                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 380                 break;                                                  \
 381         case 2:                                                         \
 382                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 383                 break;                                                  \
 384         case 4:                                                         \
 385                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 386                 break;                                                  \
 387         case 8:                                                         \
 388                 __get_user_asm_u64(x, ptr, retval, errret);             \
 389                 break;                                                  \
 390         default:                                                        \
 391                 (x) = __get_user_bad();                                 \
 392         }                                                               \
 393 } while (0)
 394
 395 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 396         asm volatile("\n"                                               \
 397                      "1:        mov"itype" %2,%"rtype"1\n"              \
 398                      "2:\n"                                             \
 399                      ".section .fixup,\"ax\"\n"                         \
 400                      "3:        mov %3,%0\n"                            \
 401                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 402                      "  jmp 2b\n"                                       \
 403                      ".previous\n"                                      \
 404                      _ASM_EXTABLE(1b, 3b)                               \
 405                      : "=r" (err), ltype(x)                             \
 406                      : "m" (__m(addr)), "i" (errret), "0" (err))
 407
 408 /*
 409  * This doesn't do __uaccess_begin/end - the exception handling
 410  * around it must do that.
 411  */
 412 #define __get_user_size_ex(x, ptr, size)                                \
 413 do {                                                                    \
 414         __chk_user_ptr(ptr);                                            \
 415         switch (size) {                                                 \
 416         case 1:                                                         \
 417                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 418                 break;                                                  \
 419         case 2:                                                         \
 420                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 421                 break;                                                  \
 422         case 4:                                                         \
 423                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 424                 break;                                                  \
 425         case 8:                                                         \
 426                 __get_user_asm_ex_u64(x, ptr);                          \
 427                 break;                                                  \
 428         default:                                                        \
 429                 (x) = __get_user_bad();                                 \
 430         }                                                               \
 431 } while (0)
 432
 433 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 434         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 435                      "2:\n"                                             \
 436                      _ASM_EXTABLE_EX(1b, 2b)                            \
 437                      : ltype(x) : "m" (__m(addr)))
 438
 439 #define __put_user_nocheck(x, ptr, size)                        \
 440 ({                                                              \
 441         int __pu_err;                                           \
 442         __uaccess_begin();                                      \
 443         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 444         __uaccess_end();                                        \
 445         __builtin_expect(__pu_err, 0);                          \
 446 })
 447
 448 #define __get_user_nocheck(x, ptr, size)                                \
 449 ({                                                                      \
 450         int __gu_err;                                                   \
 451         __inttype(*(ptr)) __gu_val;                                     \
 452         __uaccess_begin();                                              \
 453         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 454         __uaccess_end();                                                \
 455         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 456         __builtin_expect(__gu_err, 0);                                  \
 457 })
 458
 459 /* FIXME: this hack is definitely wrong -AK */
 460 struct __large_struct { unsigned long buf[100]; };
 461 #define __m(x) (*(struct __large_struct __user *)(x))
 462
 463 /*
 464  * Tell gcc we read from memory instead of writing: this is because
 465  * we do not write to any memory gcc knows about, so there are no
 466  * aliasing issues.
 467  */
 468 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 469         asm volatile("\n"                                               \
 470                      "1:        mov"itype" %"rtype"1,%2\n"              \
 471                      "2:\n"                                             \
 472                      ".section .fixup,\"ax\"\n"                         \
 473                      "3:        mov %3,%0\n"                            \
 474                      "  jmp 2b\n"                                       \
 475                      ".previous\n"                                      \
 476                      _ASM_EXTABLE(1b, 3b)                               \
 477                      : "=r"(err)                                        \
 478                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 479
 480 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 481         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 482                      "2:\n"                                             \
 483                      _ASM_EXTABLE_EX(1b, 2b)                            \
 484                      : : ltype(x), "m" (__m(addr)))
 485
 486 /*
 487  * uaccess_try and catch
 488  */
 489 #define uaccess_try     do {                                            \
 490         current->thread.uaccess_err = 0;                                \
 491         __uaccess_begin();                                              \
 492         barrier();
 493
 494 #define uaccess_catch(err)                                              \
 495         __uaccess_end();                                                \
 496         (err) |= (current->thread.uaccess_err ? -EFAULT : 0);           \
 497 } while (0)
 498
 499 /**
 500  * __get_user: - Get a simple variable from user space, with less checking.
 501  * @x:   Variable to store result.
 502  * @ptr: Source address, in user space.
 503  *
 504  * Context: User context only. This function may sleep if pagefaults are
 505  *          enabled.
 506  *
 507  * This macro copies a single simple variable from user space to kernel
 508  * space.  It supports simple types like char and int, but not larger
 509  * data types like structures or arrays.
 510  *
 511  * @ptr must have pointer-to-simple-variable type, and the result of
 512  * dereferencing @ptr must be assignable to @x without a cast.
 513  *
 514  * Caller must check the pointer with access_ok() before calling this
 515  * function.
 516  *
 517  * Returns zero on success, or -EFAULT on error.
 518  * On error, the variable @x is set to zero.
 519  */
 520
 521 #define __get_user(x, ptr)                                              \
 522         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 523
 524 /**
 525  * __put_user: - Write a simple value into user space, with less checking.
 526  * @x:   Value to copy to user space.
 527  * @ptr: Destination address, in user space.
 528  *
 529  * Context: User context only. This function may sleep if pagefaults are
 530  *          enabled.
 531  *
 532  * This macro copies a single simple value from kernel space to user
 533  * space.  It supports simple types like char and int, but not larger
 534  * data types like structures or arrays.
 535  *
 536  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 537  * to the result of dereferencing @ptr.
 538  *
 539  * Caller must check the pointer with access_ok() before calling this
 540  * function.
 541  *
 542  * Returns zero on success, or -EFAULT on error.
 543  */
 544
 545 #define __put_user(x, ptr)                                              \
 546         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 547
 548 #define __get_user_unaligned __get_user
 549 #define __put_user_unaligned __put_user
 550
 551 /*
 552  * {get|put}_user_try and catch
 553  *
 554  * get_user_try {
 555  *      get_user_ex(...);
 556  * } get_user_catch(err)
 557  */
 558 #define get_user_try            uaccess_try
 559 #define get_user_catch(err)     uaccess_catch(err)
 560
 561 #define get_user_ex(x, ptr)     do {                                    \
 562         unsigned long __gue_val;                                        \
 563         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 564         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 565 } while (0)
 566
 567 #define put_user_try            uaccess_try
 568 #define put_user_catch(err)     uaccess_catch(err)
 569
 570 #define put_user_ex(x, ptr)                                             \
 571         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 572
 573 extern unsigned long
 574 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 575 extern __must_check long
 576 strncpy_from_user(char *dst, const char __user *src, long count);
 577
 578 extern __must_check long strlen_user(const char __user *str);
 579 extern __must_check long strnlen_user(const char __user *str, long n);
 580
 581 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 582 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 583
 584 extern void __cmpxchg_wrong_size(void)
 585         __compiletime_error("Bad argument size for cmpxchg");
 586
 587 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 588 ({                                                                      \
 589         int __ret = 0;                                                  \
 590         __typeof__(ptr) __uval = (uval);                                \
 591         __typeof__(*(ptr)) __old = (old);                               \
 592         __typeof__(*(ptr)) __new = (new);                               \
 593         __uaccess_begin();                                              \
 594         switch (size) {                                                 \
 595         case 1:                                                         \
 596         {                                                               \
 597                 asm volatile("\n"                                       \
 598                         "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 599                         "2:\n"                                          \
 600                         "\t.section .fixup, \"ax\"\n"                   \
 601                         "3:\tmov     %3, %0\n"                          \
 602                         "\tjmp     2b\n"                                \
 603                         "\t.previous\n"                                 \
 604                         _ASM_EXTABLE(1b, 3b)                            \
 605                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 606                         : "i" (-EFAULT), "q" (__new), "1" (__old)       \
 607                         : "memory"                                      \
 608                 );                                                      \
 609                 break;                                                  \
 610         }                                                               \
 611         case 2:                                                         \
 612         {                                                               \
 613                 asm volatile("\n"                                       \
 614                         "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 615                         "2:\n"                                          \
 616                         "\t.section .fixup, \"ax\"\n"                   \
 617                         "3:\tmov     %3, %0\n"                          \
 618                         "\tjmp     2b\n"                                \
 619                         "\t.previous\n"                                 \
 620                         _ASM_EXTABLE(1b, 3b)                            \
 621                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 622                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 623                         : "memory"                                      \
 624                 );                                                      \
 625                 break;                                                  \
 626         }                                                               \
 627         case 4:                                                         \
 628         {                                                               \
 629                 asm volatile("\n"                                       \
 630                         "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 631                         "2:\n"                                          \
 632                         "\t.section .fixup, \"ax\"\n"                   \
 633                         "3:\tmov     %3, %0\n"                          \
 634                         "\tjmp     2b\n"                                \
 635                         "\t.previous\n"                                 \
 636                         _ASM_EXTABLE(1b, 3b)                            \
 637                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 638                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 639                         : "memory"                                      \
 640                 );                                                      \
 641                 break;                                                  \
 642         }                                                               \
 643         case 8:                                                         \
 644         {                                                               \
 645                 if (!IS_ENABLED(CONFIG_X86_64))                         \
 646                         __cmpxchg_wrong_size();                         \
 647                                                                         \
 648                 asm volatile("\n"                                       \
 649                         "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 650                         "2:\n"                                          \
 651                         "\t.section .fixup, \"ax\"\n"                   \
 652                         "3:\tmov     %3, %0\n"                          \
 653                         "\tjmp     2b\n"                                \
 654                         "\t.previous\n"                                 \
 655                         _ASM_EXTABLE(1b, 3b)                            \
 656                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 657                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 658                         : "memory"                                      \
 659                 );                                                      \
 660                 break;                                                  \
 661         }                                                               \
 662         default:                                                        \
 663                 __cmpxchg_wrong_size();                                 \
 664         }                                                               \
 665         __uaccess_end();                                                \
 666         *__uval = __old;                                                \
 667         __ret;                                                          \
 668 })
 669
 670 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 671 ({                                                                      \
 672         access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ?                \
 673                 __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 674                                 (old), (new), sizeof(*(ptr))) :         \
 675                 -EFAULT;                                                \
 676 })
 677
 678 /*
 679  * movsl can be slow when source and dest are not both 8-byte aligned
 680  */
 681 #ifdef CONFIG_X86_INTEL_USERCOPY
 682 extern struct movsl_mask {
 683         int mask;
 684 } ____cacheline_aligned_in_smp movsl_mask;
 685 #endif
 686
 687 #define ARCH_HAS_NOCACHE_UACCESS 1
 688
 689 #ifdef CONFIG_X86_32
 690 # include <asm/uaccess_32.h>
 691 #else
 692 # include <asm/uaccess_64.h>
 693 #endif
 694
 695 unsigned long __must_check _copy_from_user(void *to, const void __user *from,
 696                                            unsigned n);
 697 unsigned long __must_check _copy_to_user(void __user *to, const void *from,
 698                                          unsigned n);
 699
 700 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 701 # define copy_user_diag __compiletime_error
 702 #else
 703 # define copy_user_diag __compiletime_warning
 704 #endif
 705
 706 extern void copy_user_diag("copy_from_user() buffer size is too small")
 707 copy_from_user_overflow(void);
 708 extern void copy_user_diag("copy_to_user() buffer size is too small")
 709 copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
 710
 711 #undef copy_user_diag
 712
 713 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 714
 715 extern void
 716 __compiletime_warning("copy_from_user() buffer size is not provably correct")
 717 __copy_from_user_overflow(void) __asm__("copy_from_user_overflow");
 718 #define __copy_from_user_overflow(size, count) __copy_from_user_overflow()
 719
 720 extern void
 721 __compiletime_warning("copy_to_user() buffer size is not provably correct")
 722 __copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
 723 #define __copy_to_user_overflow(size, count) __copy_to_user_overflow()
 724
 725 #else
 726
 727 static inline void
 728 __copy_from_user_overflow(int size, unsigned long count)
 729 {
 730         WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
 731 }
 732
 733 #define __copy_to_user_overflow __copy_from_user_overflow
 734
 735 #endif
 736
 737 static inline unsigned long __must_check
 738 copy_from_user(void *to, const void __user *from, unsigned long n)
 739 {
 740         int sz = __compiletime_object_size(to);
 741
 742         might_fault();
 743
 744         kasan_check_write(to, n);
 745
 746         /*
 747          * While we would like to have the compiler do the checking for us
 748          * even in the non-constant size case, any false positives there are
 749          * a problem (especially when DEBUG_STRICT_USER_COPY_CHECKS, but even
 750          * without - the [hopefully] dangerous looking nature of the warning
 751          * would make people go look at the respecitive call sites over and
 752          * over again just to find that there's no problem).
 753          *
 754          * And there are cases where it's just not realistic for the compiler
 755          * to prove the count to be in range. For example when multiple call
 756          * sites of a helper function - perhaps in different source files -
 757          * all doing proper range checking, yet the helper function not doing
 758          * so again.
 759          *
 760          * Therefore limit the compile time checking to the constant size
 761          * case, and do only runtime checking for non-constant sizes.
 762          */
 763
 764         if (likely(sz < 0 || sz >= n)) {
 765                 check_object_size(to, n, false);
 766                 n = _copy_from_user(to, from, n);
 767         } else if (__builtin_constant_p(n))
 768                 copy_from_user_overflow();
 769         else
 770                 __copy_from_user_overflow(sz, n);
 771
 772         return n;
 773 }
 774
 775 static inline unsigned long __must_check
 776 copy_to_user(void __user *to, const void *from, unsigned long n)
 777 {
 778         int sz = __compiletime_object_size(from);
 779
 780         kasan_check_read(from, n);
 781
 782         might_fault();
 783
 784         /* See the comment in copy_from_user() above. */
 785         if (likely(sz < 0 || sz >= n)) {
 786                 check_object_size(from, n, true);
 787                 n = _copy_to_user(to, from, n);
 788         } else if (__builtin_constant_p(n))
 789                 copy_to_user_overflow();
 790         else
 791                 __copy_to_user_overflow(sz, n);
 792
 793         return n;
 794 }
 795
 796 #undef __copy_from_user_overflow
 797 #undef __copy_to_user_overflow
 798
 799 /*
 800  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
 801  * nested NMI paths are careful to preserve CR2.
 802  *
 803  * Caller must use pagefault_enable/disable, or run in interrupt context,
 804  * and also do a uaccess_ok() check
 805  */
 806 #define __copy_from_user_nmi __copy_from_user_inatomic
 807
 808 /*
 809  * The "unsafe" user accesses aren't really "unsafe", but the naming
 810  * is a big fat warning: you have to not only do the access_ok()
 811  * checking before using them, but you have to surround them with the
 812  * user_access_begin/end() pair.
 813  */
 814 #define user_access_begin()     __uaccess_begin()
 815 #define user_access_end()       __uaccess_end()
 816
 817 #define unsafe_put_user(x, ptr, err_label)                                      \
 818 do {                                                                            \
 819         int __pu_err;                                                           \
 820         __put_user_size((x), (ptr), sizeof(*(ptr)), __pu_err, -EFAULT);         \
 821         if (unlikely(__pu_err)) goto err_label;                                 \
 822 } while (0)
 823
 824 #define unsafe_get_user(x, ptr, err_label)                                      \
 825 do {                                                                            \
 826         int __gu_err;                                                           \
 827         unsigned long __gu_val;                                                 \
 828         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);    \
 829         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 830         if (unlikely(__gu_err)) goto err_label;                                 \
 831 } while (0)
 832
 833 #endif /* _ASM_X86_UACCESS_H */
 834