arch/x86/include/asm/uaccess.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_X86_UACCESS_H
   3 #define _ASM_X86_UACCESS_H
   4 /*
   5  * User space memory access functions
   6  */
   7 #include <linux/compiler.h>
   8 #include <linux/kasan-checks.h>
   9 #include <linux/string.h>
  10 #include <asm/asm.h>
  11 #include <asm/page.h>
  12 #include <asm/smap.h>
  13 #include <asm/extable.h>
  14
  15 /*
  16  * Test whether a block of memory is a valid user space address.
  17  * Returns 0 if the range is valid, nonzero otherwise.
  18  */
  19 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
  20 {
  21         /*
  22          * If we have used "sizeof()" for the size,
  23          * we know it won't overflow the limit (but
  24          * it might overflow the 'addr', so it's
  25          * important to subtract the size from the
  26          * limit, not add it to the address).
  27          */
  28         if (__builtin_constant_p(size))
  29                 return unlikely(addr > limit - size);
  30
  31         /* Arbitrary sizes? Be careful about overflow */
  32         addr += size;
  33         if (unlikely(addr < size))
  34                 return true;
  35         return unlikely(addr > limit);
  36 }
  37
  38 #define __range_not_ok(addr, size, limit)                               \
  39 ({                                                                      \
  40         __chk_user_ptr(addr);                                           \
  41         __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
  42 })
  43
  44 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
  45 static inline bool pagefault_disabled(void);
  46 # define WARN_ON_IN_IRQ()       \
  47         WARN_ON_ONCE(!in_task() && !pagefault_disabled())
  48 #else
  49 # define WARN_ON_IN_IRQ()
  50 #endif
  51
  52 /**
  53  * access_ok - Checks if a user space pointer is valid
  54  * @addr: User space pointer to start of block to check
  55  * @size: Size of block to check
  56  *
  57  * Context: User context only. This function may sleep if pagefaults are
  58  *          enabled.
  59  *
  60  * Checks if a pointer to a block of memory in user space is valid.
  61  *
  62  * Note that, depending on architecture, this function probably just
  63  * checks that the pointer is in the user space range - after calling
  64  * this function, memory access functions may still return -EFAULT.
  65  *
  66  * Return: true (nonzero) if the memory block may be valid, false (zero)
  67  * if it is definitely invalid.
  68  */
  69 #define access_ok(addr, size)                                   \
  70 ({                                                                      \
  71         WARN_ON_IN_IRQ();                                               \
  72         likely(!__range_not_ok(addr, size, TASK_SIZE_MAX));             \
  73 })
  74
  75 extern int __get_user_1(void);
  76 extern int __get_user_2(void);
  77 extern int __get_user_4(void);
  78 extern int __get_user_8(void);
  79 extern int __get_user_nocheck_1(void);
  80 extern int __get_user_nocheck_2(void);
  81 extern int __get_user_nocheck_4(void);
  82 extern int __get_user_nocheck_8(void);
  83 extern int __get_user_bad(void);
  84
  85 #define __uaccess_begin() stac()
  86 #define __uaccess_end()   clac()
  87 #define __uaccess_begin_nospec()        \
  88 ({                                      \
  89         stac();                         \
  90         barrier_nospec();               \
  91 })
  92
  93 /*
  94  * This is the smallest unsigned integer type that can fit a value
  95  * (up to 'long long')
  96  */
  97 #define __inttype(x) __typeof__(                \
  98         __typefits(x,char,                      \
  99           __typefits(x,short,                   \
 100             __typefits(x,int,                   \
 101               __typefits(x,long,0ULL)))))
 102
 103 #define __typefits(x,type,not) \
 104         __builtin_choose_expr(sizeof(x)<=sizeof(type),(unsigned type)0,not)
 105
 106 /*
 107  * This is used for both get_user() and __get_user() to expand to
 108  * the proper special function call that has odd calling conventions
 109  * due to returning both a value and an error, and that depends on
 110  * the size of the pointer passed in.
 111  *
 112  * Careful: we have to cast the result to the type of the pointer
 113  * for sign reasons.
 114  *
 115  * The use of _ASM_DX as the register specifier is a bit of a
 116  * simplification, as gcc only cares about it as the starting point
 117  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 118  * (%ecx being the next register in gcc's x86 register sequence), and
 119  * %rdx on 64 bits.
 120  *
 121  * Clang/LLVM cares about the size of the register, but still wants
 122  * the base register for something that ends up being a pair.
 123  */
 124 #define do_get_user_call(fn,x,ptr)                                      \
 125 ({                                                                      \
 126         int __ret_gu;                                                   \
 127         register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 128         __chk_user_ptr(ptr);                                            \
 129         asm volatile("call __" #fn "_%P4"                               \
 130                      : "=a" (__ret_gu), "=r" (__val_gu),                \
 131                         ASM_CALL_CONSTRAINT                             \
 132                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 133         (x) = (__force __typeof__(*(ptr))) __val_gu;                    \
 134         __builtin_expect(__ret_gu, 0);                                  \
 135 })
 136
 137 /**
 138  * get_user - Get a simple variable from user space.
 139  * @x:   Variable to store result.
 140  * @ptr: Source address, in user space.
 141  *
 142  * Context: User context only. This function may sleep if pagefaults are
 143  *          enabled.
 144  *
 145  * This macro copies a single simple variable from user space to kernel
 146  * space.  It supports simple types like char and int, but not larger
 147  * data types like structures or arrays.
 148  *
 149  * @ptr must have pointer-to-simple-variable type, and the result of
 150  * dereferencing @ptr must be assignable to @x without a cast.
 151  *
 152  * Return: zero on success, or -EFAULT on error.
 153  * On error, the variable @x is set to zero.
 154  */
 155 #define get_user(x,ptr) ({ might_fault(); do_get_user_call(get_user,x,ptr); })
 156
 157 /**
 158  * __get_user - Get a simple variable from user space, with less checking.
 159  * @x:   Variable to store result.
 160  * @ptr: Source address, in user space.
 161  *
 162  * Context: User context only. This function may sleep if pagefaults are
 163  *          enabled.
 164  *
 165  * This macro copies a single simple variable from user space to kernel
 166  * space.  It supports simple types like char and int, but not larger
 167  * data types like structures or arrays.
 168  *
 169  * @ptr must have pointer-to-simple-variable type, and the result of
 170  * dereferencing @ptr must be assignable to @x without a cast.
 171  *
 172  * Caller must check the pointer with access_ok() before calling this
 173  * function.
 174  *
 175  * Return: zero on success, or -EFAULT on error.
 176  * On error, the variable @x is set to zero.
 177  */
 178 #define __get_user(x,ptr) do_get_user_call(get_user_nocheck,x,ptr)
 179
 180
 181 #ifdef CONFIG_X86_32
 182 #define __put_user_goto_u64(x, addr, label)                     \
 183         asm_volatile_goto("\n"                                  \
 184                      "1:        movl %%eax,0(%1)\n"             \
 185                      "2:        movl %%edx,4(%1)\n"             \
 186                      _ASM_EXTABLE_UA(1b, %l2)                   \
 187                      _ASM_EXTABLE_UA(2b, %l2)                   \
 188                      : : "A" (x), "r" (addr)                    \
 189                      : : label)
 190
 191 #else
 192 #define __put_user_goto_u64(x, ptr, label) \
 193         __put_user_goto(x, ptr, "q", "er", label)
 194 #endif
 195
 196 extern void __put_user_bad(void);
 197
 198 /*
 199  * Strange magic calling convention: pointer in %ecx,
 200  * value in %eax(:%edx), return value in %ecx. clobbers %rbx
 201  */
 202 extern void __put_user_1(void);
 203 extern void __put_user_2(void);
 204 extern void __put_user_4(void);
 205 extern void __put_user_8(void);
 206 extern void __put_user_nocheck_1(void);
 207 extern void __put_user_nocheck_2(void);
 208 extern void __put_user_nocheck_4(void);
 209 extern void __put_user_nocheck_8(void);
 210
 211 /*
 212  * ptr must be evaluated and assigned to the temporary __ptr_pu before
 213  * the assignment of x to __val_pu, to avoid any function calls
 214  * involved in the ptr expression (possibly implicitly generated due
 215  * to KASAN) from clobbering %ax.
 216  */
 217 #define do_put_user_call(fn,x,ptr)                                      \
 218 ({                                                                      \
 219         int __ret_pu;                                                   \
 220         void __user *__ptr_pu;                                          \
 221         register __typeof__(*(ptr)) __val_pu asm("%"_ASM_AX);           \
 222         __chk_user_ptr(ptr);                                            \
 223         __ptr_pu = (ptr);                                               \
 224         __val_pu = (x);                                                 \
 225         asm volatile("call __" #fn "_%P[size]"                          \
 226                      : "=c" (__ret_pu),                                 \
 227                         ASM_CALL_CONSTRAINT                             \
 228                      : "0" (__ptr_pu),                                  \
 229                        "r" (__val_pu),                                  \
 230                        [size] "i" (sizeof(*(ptr)))                      \
 231                      :"ebx");                                           \
 232         __builtin_expect(__ret_pu, 0);                                  \
 233 })
 234
 235 /**
 236  * put_user - Write a simple value into user space.
 237  * @x:   Value to copy to user space.
 238  * @ptr: Destination address, in user space.
 239  *
 240  * Context: User context only. This function may sleep if pagefaults are
 241  *          enabled.
 242  *
 243  * This macro copies a single simple value from kernel space to user
 244  * space.  It supports simple types like char and int, but not larger
 245  * data types like structures or arrays.
 246  *
 247  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 248  * to the result of dereferencing @ptr.
 249  *
 250  * Return: zero on success, or -EFAULT on error.
 251  */
 252 #define put_user(x, ptr) ({ might_fault(); do_put_user_call(put_user,x,ptr); })
 253
 254 /**
 255  * __put_user - Write a simple value into user space, with less checking.
 256  * @x:   Value to copy to user space.
 257  * @ptr: Destination address, in user space.
 258  *
 259  * Context: User context only. This function may sleep if pagefaults are
 260  *          enabled.
 261  *
 262  * This macro copies a single simple value from kernel space to user
 263  * space.  It supports simple types like char and int, but not larger
 264  * data types like structures or arrays.
 265  *
 266  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 267  * to the result of dereferencing @ptr.
 268  *
 269  * Caller must check the pointer with access_ok() before calling this
 270  * function.
 271  *
 272  * Return: zero on success, or -EFAULT on error.
 273  */
 274 #define __put_user(x, ptr) do_put_user_call(put_user_nocheck,x,ptr)
 275
 276 #define __put_user_size(x, ptr, size, label)                            \
 277 do {                                                                    \
 278         __chk_user_ptr(ptr);                                            \
 279         switch (size) {                                                 \
 280         case 1:                                                         \
 281                 __put_user_goto(x, ptr, "b", "iq", label);              \
 282                 break;                                                  \
 283         case 2:                                                         \
 284                 __put_user_goto(x, ptr, "w", "ir", label);              \
 285                 break;                                                  \
 286         case 4:                                                         \
 287                 __put_user_goto(x, ptr, "l", "ir", label);              \
 288                 break;                                                  \
 289         case 8:                                                         \
 290                 __put_user_goto_u64(x, ptr, label);                     \
 291                 break;                                                  \
 292         default:                                                        \
 293                 __put_user_bad();                                       \
 294         }                                                               \
 295 } while (0)
 296
 297 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
 298
 299 #ifdef CONFIG_X86_32
 300 #define __get_user_asm_u64(x, ptr, label) do {                          \
 301         unsigned int __gu_low, __gu_high;                               \
 302         const unsigned int __user *__gu_ptr;                            \
 303         __gu_ptr = (const void __user *)(ptr);                          \
 304         __get_user_asm(__gu_low, ptr, "l", "=r", label);                \
 305         __get_user_asm(__gu_high, ptr+1, "l", "=r", label);             \
 306         (x) = ((unsigned long long)__gu_high << 32) | __gu_low;         \
 307 } while (0)
 308 #else
 309 #define __get_user_asm_u64(x, ptr, label)                               \
 310         __get_user_asm(x, ptr, "q", "=r", label)
 311 #endif
 312
 313 #define __get_user_size(x, ptr, size, label)                            \
 314 do {                                                                    \
 315         __chk_user_ptr(ptr);                                            \
 316         switch (size) {                                                 \
 317         unsigned char x_u8__;                                           \
 318         case 1:                                                         \
 319                 __get_user_asm(x_u8__, ptr, "b", "=q", label);          \
 320                 (x) = x_u8__;                                           \
 321                 break;                                                  \
 322         case 2:                                                         \
 323                 __get_user_asm(x, ptr, "w", "=r", label);               \
 324                 break;                                                  \
 325         case 4:                                                         \
 326                 __get_user_asm(x, ptr, "l", "=r", label);               \
 327                 break;                                                  \
 328         case 8:                                                         \
 329                 __get_user_asm_u64(x, ptr, label);                      \
 330                 break;                                                  \
 331         default:                                                        \
 332                 (x) = __get_user_bad();                                 \
 333         }                                                               \
 334 } while (0)
 335
 336 #define __get_user_asm(x, addr, itype, ltype, label)                    \
 337         asm_volatile_goto("\n"                                          \
 338                      "1:        mov"itype" %[umem],%[output]\n"         \
 339                      _ASM_EXTABLE_UA(1b, %l2)                           \
 340                      : [output] ltype(x)                                \
 341                      : [umem] "m" (__m(addr))                           \
 342                      : : label)
 343
 344 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT
 345
 346 #ifdef CONFIG_X86_32
 347 #define __get_user_asm_u64(x, ptr, retval)                              \
 348 ({                                                                      \
 349         __typeof__(ptr) __ptr = (ptr);                                  \
 350         asm volatile("\n"                                               \
 351                      "1:        movl %[lowbits],%%eax\n"                \
 352                      "2:        movl %[highbits],%%edx\n"               \
 353                      "3:\n"                                             \
 354                      ".section .fixup,\"ax\"\n"                         \
 355                      "4:        mov %[efault],%[errout]\n"              \
 356                      "  xorl %%eax,%%eax\n"                             \
 357                      "  xorl %%edx,%%edx\n"                             \
 358                      "  jmp 3b\n"                                       \
 359                      ".previous\n"                                      \
 360                      _ASM_EXTABLE_UA(1b, 4b)                            \
 361                      _ASM_EXTABLE_UA(2b, 4b)                            \
 362                      : [errout] "=r" (retval),                          \
 363                        [output] "=&A"(x)                                \
 364                      : [lowbits] "m" (__m(__ptr)),                      \
 365                        [highbits] "m" __m(((u32 __user *)(__ptr)) + 1), \
 366                        [efault] "i" (-EFAULT), "0" (retval));           \
 367 })
 368
 369 #else
 370 #define __get_user_asm_u64(x, ptr, retval) \
 371          __get_user_asm(x, ptr, retval, "q", "=r")
 372 #endif
 373
 374 #define __get_user_size(x, ptr, size, retval)                           \
 375 do {                                                                    \
 376         unsigned char x_u8__;                                           \
 377                                                                         \
 378         retval = 0;                                                     \
 379         __chk_user_ptr(ptr);                                            \
 380         switch (size) {                                                 \
 381         case 1:                                                         \
 382                 __get_user_asm(x_u8__, ptr, retval, "b", "=q");         \
 383                 (x) = x_u8__;                                           \
 384                 break;                                                  \
 385         case 2:                                                         \
 386                 __get_user_asm(x, ptr, retval, "w", "=r");              \
 387                 break;                                                  \
 388         case 4:                                                         \
 389                 __get_user_asm(x, ptr, retval, "l", "=r");              \
 390                 break;                                                  \
 391         case 8:                                                         \
 392                 __get_user_asm_u64(x, ptr, retval);                     \
 393                 break;                                                  \
 394         default:                                                        \
 395                 (x) = __get_user_bad();                                 \
 396         }                                                               \
 397 } while (0)
 398
 399 #define __get_user_asm(x, addr, err, itype, ltype)                      \
 400         asm volatile("\n"                                               \
 401                      "1:        mov"itype" %[umem],%[output]\n"         \
 402                      "2:\n"                                             \
 403                      ".section .fixup,\"ax\"\n"                         \
 404                      "3:        mov %[efault],%[errout]\n"              \
 405                      "  xorl %k[output],%k[output]\n"                   \
 406                      "  jmp 2b\n"                                       \
 407                      ".previous\n"                                      \
 408                      _ASM_EXTABLE_UA(1b, 3b)                            \
 409                      : [errout] "=r" (err),                             \
 410                        [output] ltype(x)                                \
 411                      : [umem] "m" (__m(addr)),                          \
 412                        [efault] "i" (-EFAULT), "0" (err))
 413
 414 #endif // CONFIG_CC_ASM_GOTO_OUTPUT
 415
 416 /* FIXME: this hack is definitely wrong -AK */
 417 struct __large_struct { unsigned long buf[100]; };
 418 #define __m(x) (*(struct __large_struct __user *)(x))
 419
 420 /*
 421  * Tell gcc we read from memory instead of writing: this is because
 422  * we do not write to any memory gcc knows about, so there are no
 423  * aliasing issues.
 424  */
 425 #define __put_user_goto(x, addr, itype, ltype, label)                   \
 426         asm_volatile_goto("\n"                                          \
 427                 "1:     mov"itype" %0,%1\n"                             \
 428                 _ASM_EXTABLE_UA(1b, %l2)                                \
 429                 : : ltype(x), "m" (__m(addr))                           \
 430                 : : label)
 431
 432 extern unsigned long
 433 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 434 extern __must_check long
 435 strncpy_from_user(char *dst, const char __user *src, long count);
 436
 437 extern __must_check long strnlen_user(const char __user *str, long n);
 438
 439 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 440 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 441
 442 #ifdef CONFIG_ARCH_HAS_COPY_MC
 443 unsigned long __must_check
 444 copy_mc_to_kernel(void *to, const void *from, unsigned len);
 445 #define copy_mc_to_kernel copy_mc_to_kernel
 446
 447 unsigned long __must_check
 448 copy_mc_to_user(void *to, const void *from, unsigned len);
 449 #endif
 450
 451 /*
 452  * movsl can be slow when source and dest are not both 8-byte aligned
 453  */
 454 #ifdef CONFIG_X86_INTEL_USERCOPY
 455 extern struct movsl_mask {
 456         int mask;
 457 } ____cacheline_aligned_in_smp movsl_mask;
 458 #endif
 459
 460 #define ARCH_HAS_NOCACHE_UACCESS 1
 461
 462 #ifdef CONFIG_X86_32
 463 # include <asm/uaccess_32.h>
 464 #else
 465 # include <asm/uaccess_64.h>
 466 #endif
 467
 468 /*
 469  * The "unsafe" user accesses aren't really "unsafe", but the naming
 470  * is a big fat warning: you have to not only do the access_ok()
 471  * checking before using them, but you have to surround them with the
 472  * user_access_begin/end() pair.
 473  */
 474 static __must_check __always_inline bool user_access_begin(const void __user *ptr, size_t len)
 475 {
 476         if (unlikely(!access_ok(ptr,len)))
 477                 return 0;
 478         __uaccess_begin_nospec();
 479         return 1;
 480 }
 481 #define user_access_begin(a,b)  user_access_begin(a,b)
 482 #define user_access_end()       __uaccess_end()
 483
 484 #define user_access_save()      smap_save()
 485 #define user_access_restore(x)  smap_restore(x)
 486
 487 #define unsafe_put_user(x, ptr, label)  \
 488         __put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label)
 489
 490 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
 491 #define unsafe_get_user(x, ptr, err_label)                                      \
 492 do {                                                                            \
 493         __inttype(*(ptr)) __gu_val;                                             \
 494         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), err_label);            \
 495         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 496 } while (0)
 497 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT
 498 #define unsafe_get_user(x, ptr, err_label)                                      \
 499 do {                                                                            \
 500         int __gu_err;                                                           \
 501         __inttype(*(ptr)) __gu_val;                                             \
 502         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err);             \
 503         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 504         if (unlikely(__gu_err)) goto err_label;                                 \
 505 } while (0)
 506 #endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT
 507
 508 /*
 509  * We want the unsafe accessors to always be inlined and use
 510  * the error labels - thus the macro games.
 511  */
 512 #define unsafe_copy_loop(dst, src, len, type, label)                            \
 513         while (len >= sizeof(type)) {                                           \
 514                 unsafe_put_user(*(type *)(src),(type __user *)(dst),label);     \
 515                 dst += sizeof(type);                                            \
 516                 src += sizeof(type);                                            \
 517                 len -= sizeof(type);                                            \
 518         }
 519
 520 #define unsafe_copy_to_user(_dst,_src,_len,label)                       \
 521 do {                                                                    \
 522         char __user *__ucu_dst = (_dst);                                \
 523         const char *__ucu_src = (_src);                                 \
 524         size_t __ucu_len = (_len);                                      \
 525         unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u64, label);  \
 526         unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u32, label);  \
 527         unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u16, label);  \
 528         unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label);   \
 529 } while (0)
 530
 531 #define HAVE_GET_KERNEL_NOFAULT
 532
 533 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
 534 #define __get_kernel_nofault(dst, src, type, err_label)                 \
 535         __get_user_size(*((type *)(dst)), (__force type __user *)(src), \
 536                         sizeof(type), err_label)
 537 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT
 538 #define __get_kernel_nofault(dst, src, type, err_label)                 \
 539 do {                                                                    \
 540         int __kr_err;                                                   \
 541                                                                         \
 542         __get_user_size(*((type *)(dst)), (__force type __user *)(src), \
 543                         sizeof(type), __kr_err);                        \
 544         if (unlikely(__kr_err))                                         \
 545                 goto err_label;                                         \
 546 } while (0)
 547 #endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT
 548
 549 #define __put_kernel_nofault(dst, src, type, err_label)                 \
 550         __put_user_size(*((type *)(src)), (__force type __user *)(dst), \
 551                         sizeof(type), err_label)
 552
 553 #endif /* _ASM_X86_UACCESS_H */
 554